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Advanced Engineering Statistics -Multiple Linear
                   Regression


                              Project 2
                       Instructor: Dr.Victoria Chen




Group Members :
    Rakesh Raj. N
    Jaime Sanguino
    Shriraam Madanagopal
Introduction to Multiple Linear Regressions:

The Multiple Linear Regression is to learn more about the relationship between several independent or
predictor variables and a dependent or criterion variable. The Objective of this project is to develop a best
multiple linear regression model for the response variable and the Regressors (set of predictor variables). A
statistical technique that uses several explanatory variables to predict the outcome of a response variable. The
goal of multiple linear regressions (MLR) is to model the relationship between the explanatory and response
variables.

The model for MLR, given n observations, is:

yi = B0 + B1xi1 + B2xi2 + ... + Bpxip + Ei where i = 1, 2, n

MLR takes a group of random variables and tries to find a mathematical relationship between them. The
model creates a relationship in the form of a straight line (linear) that best approximates all the individual data
points.

MLR is often used to determine how many specific factors such as, the price of a commodity, interest
rates, and particular industries or sectors, influence the price movement of an asset. For example, the current
price of oil, lending rates, and the price movement of oil futures, can all have an effect on the price of an oil
company's stock price. MLR could be used to model the impact that each of these variables have on stock's
price.

Our Project:

The water line at America’s Beverage Company (Kroger Manufacturing) is the main source of income for the
manufacturing plant and the number of cases of water produced during the month of October was 591,092.
Also, there are three (3) more soft drinks lines, which are not returning the pertinent dividends because of
marketing purposes but increasing costs of production for the facility. At this point, it is imperative to
maximize the number of water cases processed in the water line in order to keep the plant running and justify
any capital appropriation requested to the General Office.

  Industrial Engineering concepts suggest that the minimization of downtime scheduled, not scheduled
downtime and set up time and the maximization of the running time and efficiency of the equipment.
Achieving these objectives will allow the enhancement of profits generated from the automated water line.




DISCUSSION:

    Modeling as dependent variable the number the water cases produced in the line y= number of water cases
and using the predictors run time, downtime, unscheduled down time and setup time will be have the
following variables

X1: Run time, the time where the line is processing the product.

X2: Downtime, the time where preventive maintenance is used to check the performance of the equipment and
execute any repairs if necessary.

X3: Setup time, the time used to do changes on the equipment when size of bottles change.
X4: Efficiency, the key performance indicator used by management in order to check status of production.


Data Set:



Cases(Y) Runmin(X1) Downmin(X2) Setupmin(X3) Effper(X4)
33,551.0 1,027.2     222.3          177.12         80.6
24,120.0 733.2       301.7          247.60         69.9
28,800.0 885.5       257.1          292.37         75.6
36,504.0 1,094.4     249.8          93.90          81.5
34,776.0 1,061.4     89.8           288.82         90.6
35,064.0 1,071.7     348.1          20.27          74.1
31,390.0 955.0       171.9          299.87         83.6
28,008.0 846.9       99.1           314.05         88.8
33,264.0 1,159.0     101.0          180.00         79.2
27,028.0 1,260.0     0.0            180.00         64.4
22,680.0 1,019.8     240.0          180.00         54.0
31,392.0 975.5       142.4          319.97         84.3
25,992.0 782.9       270.6          373.48         74.0
17,314.0 468.2       289.1          177.55         68.6
32,327.0 963.4       205.6          242.85         83.0
11,592.0 352.4       138.7          27.22          70.8
22,104.0 660.3       134.0          0.00           83.5
173.0    5.2         0.0            0.00           99.2
36,576.0 1,108.1     291.9          39.98          78.4
24,912.0 759.0       292.2          388.82         71.1
33,509.0 1,005.0     223.7          211.35         81.8
20,016.0 618.5       492.8          297.03         54.0
As we were suggested by Dr. Chen to choose between the Not Scheduled and Down_min , we opted for
Down_min and continued with the analysis of the project.



A Methodical approach to our Project:

      In our project we have 4 predictors, the preliminary model is as mentioned below:

      Yi = β0 + β1 xi1 + β2 xi2 + β3 xi3 + β4 xi4 + εi

      i = 1,..., n observations




      X1: Run time, the time where the line is processing the product.
X2: Downtime, the time where preventive maintenance is used to check the performance of the
         equipment and execute any repairs if necessary.

         X3: Setup time, the time used to do changes on the equipment when size of bottles change.

         X4: Efficiency, the key performance indicator used by management in order to check status of
         production.

From the graph attached above, we can observe the different relations between the predictors and the response
variables, as well as the relationship between the predictors. In the above figure we find that there in no major
trend present in the X2, X3 and X5(Since we have omitted the consideration of X4 ie:- NOT SCHEDULED,we
should check the co-relation of X5). The correlation between the predictor and response variable appear to be
pretty good having a linear trend. The Predictor- Predictor plots show a pretty good scatter apart from the X1
and X4 plot. The ANOVA table below shows the various correlations between the Predictors and the response
variable . The highest correlation gives us a value of 0.85271 which indicates that the effect of Runmin has the
highest influence on the Response variable.


                                                    The CORR Procedure

                             5 Variables:     Cases   Runmin Downmin Setupmin Effper


                                                      Simple Statistics

Variable       N         Mean       Std Dev        Sum     Minimum           Maximum Label

Cases        22     26868    8888   591092 173.00000     36576 Cases
Runmin         22 855.10381 295.30889     18812  5.23333     1260 Runmin
Downmin          22 207.34846 115.36229     4562      0 492.81662 Downmin
Setupmin        22 197.82879 122.34451     4352      0 388.81667 Setupmin
Effper       22 76.86493 10.87210       1691 54.01255 99.18188 Effper


Pearson Correlation Coefficients, N = 22

Cases      Runmin         Downmin        Setupmin         Effper

Cases       1.00000       0.91564      0.18742      0.25811        0.07561

Runmin        0.91564       1.00000      0.03402      0.22376       -0.11767

Downmin         0.18742      0.03402      1.00000        0.19526     -0.57898


Setupmin       0.25811      0.22376      0.19526      1.00000       -0.14302

Effper      0.07561       -0.11767     -0.57898     -0.14302       1.00000
Our preliminary analysis suggests that bivariate relationships between the individual factors should not
cause a problem in our model so the assumptions of the model need to be evaluated to further appropriateness
of our whole model.

Model Adequacy:

The residual analysis is used to verify our model assumptions:

   1.   The current MLR Model is reasonable
   2.   The residuals have constant variance
   3.   The residuals are normally distributed
   4.   The residuals are uncorrelated
   5.   No outliers
   6.   The predictors are not highly correlated with each other.




Residuals vs. fitted values: Our preliminary fitted model is a first order four variable Linear
Equation of the form as shown below,

                            Y i = b0 + b1 xi + b2x2 + b3x3 + b4x4 + ε .i
                            ^




Cases = -28850 -24.46143* Runmin - 26.47767*Downmin -0.42515 Setup time + 388.10655 Effper

Residual V/S Fitted Value:
The residuals given by (e) represent the difference between the model and fitted values of the cases. This
comparison is useful for identifying possible outliers, checking the general form of the model and checking for
constancy of the variance of error terms. The plot of residuals vs. the fitted values is as shown below in figure.




Inference: A Funnel shape can be observed in the values between the Residual and the Fitted values. This
indicates that Constant –Variance is NOT OK . Hence we need to proceed with the transformation on Y , we
use a Square root transformation to check if the Non-Constant Variance can be improved.
Residuals vs. Predictor variables:

1 : Residuals V/S Predictors plots are as given in figures below,




The graph’s above indicate the relationship between the Residuals and the various Predictors of the Model. We
can observe a random scatter in all the plots. Since there is no curvature we can state that the current MLR
model forms are OK.

Normal probability plot:

       The plot between residuals and normal scores is as shown below.From the graph we observe a Line
which is not Straight . Hence the Normality is NOT OK .
Plots for Predictor - Predictor variables

       Below are the plots between Runmin, Downtime, Setupmin and EffPer.
Statistics project2
From above plots we can observe a proper Scatter and there is no trend or curvature in the plots are randomly
scattered with our Predictor Vs Predictor Variables.


Transformation:

A Funnel can be observed in the plot between Residual and Yhat .Hence As suggested by Dr Chen , we carried
out a Square root of “Y “ transformation . The results are as given below….Since there was not much of an
improvement which was observed . We reverted back to the old data set without any Transformations .
       The values of these are as follows :


Formal tests on constancy of variance, multi co linearity, normality of error terms, lack of fit and X or Y
outliers.


       i.   Test for normality: We conduct a correlation test for normality with value of α=.05.
             From the SAS output, we have the coefficient of correlation is given as 0.9263

             And from the given α=0.05, the test statistic we have from table B6 from the textbook is 0.9525.
             Decision rule is as given below
              H0: Normality is OK
              H1: Normality is violated
              If ρ ( e, z ) < c( α , n ) (Table B6) Reject H0
                 ˆ

              Since ρ ( e, z ) = 0.9263 ≤ c( 0.05,21) = 0.9525 ⇒ Normality is Ok.
                    ˆ
The CORR Procedure

                     2 Variables:         e2       enrm


                            Simple Statistics

 Variable       N          Mean     Std Dev             Sum    Minimum    Maximum Label

 e2         21         0       0.01188         0       -0.03180 0.02978 Residual
 enrm         21           0     0.96464           0     -1.88951 1.88951 Normal Scores


                   Pearson Correlation Coefficients, N = 21
                      Prob > |r| under H0: Rho=0

                                     e2         enrm

                   e2              1.00000         0.92630
                   Residual                        <.0001

                   enrm         0.92630    1.00000
                   Normal Scores     <.000


Test For Multicollinearity:
                   The variance inflation factors associated with various
                   predictor variables are as given below,

                     VIFrunmin= (1-Rrunmin2)-1 = 1.13198
                     VIFdowntime = (1-Rdowntime2)-1 = 1.38942
                     VIFsetuptime = (1-Rsetuptime2)-1  = 1.00751
                     VIFEffper = (1-Reffper 2)-1 = 1.33575
                     VIF bar= 1.216165 < 5

                   The result of the above VIF values is that it confirms there is little multicollinearity among
            the individual predictor variables. A VIF value near or above 5 would indicate a serious deviation
            in the variance i.e. serious multicollinearity but a perfect VIF value would be 1 which all of our
            variables are relatively close. The maximum value of 1.38942 for focal length being used as an
            indicator the total model confirms that multicollinearity is not present as suggested by earlier plots.

    BONFERRONI TEST FOR OUTLIER:
               From Figure 2, we identify the outlier as the 7th observation. It is a Y – outlier because it is in
         the Y – direction. Hence , we use Bonferroni outlier test for the outlier.
        Using the two tailed bonferroni test at α = 0.05, we have
        The Bonferroni critical value is given as,
            t(1-α/2n ; n-p-1 ) = t(1-.05/2×21 ; 21-5-1 ) = 3.286

               From the SAS output , we have the test statistic as,

                       Obs       tinvtres      finv50
1   3.29725   0.90583
The REG Procedure
                     Model: MODEL1
                  Dependent Variable: yprime

              Number of Observations Read           21
              Number of Observations Used           21


                   Analysis of Variance

                      Sum of     Mean
 Source             DF   Squares    Square          F Value   Pr > F

 Model             4    0.30425     0.07606 431.05         <.0001
 Error           16    0.00282 0.00017646
 Corrected Total     20     0.30707


           Root MSE       0.01328 R-Square 0.9908
           Dependent Mean     4.43447 Adj R-Sq 0.9885
           Coeff Var     0.29956


                    Parameter Estimates

             Parameter   Standard                       Variance
Variable     DF   Estimate     Error      t Value    Pr > |t|    Inflation

Intercept 1        3.40999    0.03197 106.66     <.0001        0
Runmin      1     0.00046190 0.00001363     33.88    <.0001     1.13198
Downmin       1     0.00047875 0.00003234    14.80    <.0001      1.38942
Setupmin    1      0.00009967 0.00002550     3.91   0.0013     1.00751
Effper    1       0.00641 0.00034657    18.51    <.0001     1.33575




                       The REG Procedure
                     Model: MODEL1
                  Dependent Variable: yprime

                    Output Statistics

                           Hat Diag       Cov
      Obs     Residual     RStudent        H    Ratio     DFFITS

       1     0.000243      0.0185  0.0839   1.5071   0.0056
       2       0.0163    1.3212   0.0962   0.8811   0.4310
       3     0.003302      0.2515  0.0805   1.4705   0.0744
       4    -0.004805     -0.3892   0.1818   1.6050 -0.1835
       5      -0.0118    -0.9941  0.1998   1.2544 -0.4968
       6    -0.004059     -0.3671   0.3445   2.0145 -0.2662
7 -0.002662       -0.2058   0.1090   1.5281 -0.0720
            8 -0.002175       -0.1791   0.2151   1.7405 -0.0938
            9 0.002376        0.1876    0.1465  1.5990    0.0777
           10 0.008857          1.1031   0.6297  2.5247    1.4384
           11 -0.004586        -0.4284   0.3837   2.1084 -0.3380
           12 -0.004503        -0.3548   0.1366   1.5339 -0.1411
           13 0.001862          0.1485   0.1635  1.6387    0.0657
           14    0.0161       1.4161   0.2244   0.9507   0.7618
           15 -0.000378        -0.0287   0.0830   1.5054 -0.0086
           16   -0.0318      -8.4950   0.5674   0.0005 -9.7298
           17    0.0298       3.6993   0.3415   0.0820   2.6641
           18 -0.005207        -0.4481   0.2731   1.7775 -0.2747
           19 0.001193          0.0970   0.1965  1.7130    0.0480
           20 -0.001818        -0.1385   0.0834   1.4968 -0.0418
           21 -0.006185        -0.6212   0.4597   2.2511 -0.5731

                        Output Statistics

              -------------------------DFBETAS-------------------------
           Obs Intercept         Runmin Downmin Setupmin                  Effper

           1     -0.0026     0.0024  0.0020        -0.0013     0.0023
           2      0.0890    -0.1393  0.1299         0.0981    -0.0646
           3     -0.0136     0.0033  0.0208         0.0409     0.0076
           4      0.0886    -0.0873 -0.0899         0.1003    -0.0737
           5      0.1991    -0.0561  0.1258        -0.1748    -0.2414
           6      0.0798    -0.1173 -0.1672         0.1730    -0.0436
           7      0.0261    -0.0022  0.0045        -0.0379    -0.0296
           8      0.0175     0.0320  0.0334        -0.0418    -0.0415
           9      0.0094     0.0395 -0.0362        -0.0071    -0.0138
           10      0.9167     0.5288 -1.0356         0.0160    -1.0440
           11     -0.2378    -0.1161  0.0890         0.0114     0.3041
           12      0.0378    -0.0048  0.0316        -0.0829    -0.0447
           13     -0.0029    -0.0130  0.0093         0.0506     0.0009
           14      0.3462    -0.6029 -0.0053        -0.0956    -0.0817
           15      0.0046    -0.0012 -0.0020        -0.0018    -0.0049
           16     -6.1126     7.5499  4.4954         4.1659     1.5784
           17      0.4446    -1.4287 -0.6237        -1.7983     0.7613




We see that observations 10,16 and 17 have absolute values greater than 1. We measure the value with respect
to 1 since the data set is less than 30 values.
16:00 Saturday, December 6, 2008 135

                         The REG Procedure
                          Model: MODEL1
                       Dependent Variable: yprime

                          Output Statistics

               -------------------------DFBETAS-------------------------
            Obs Intercept         Runmin Downmin Setupmin                  Effper

            18       0.1043    -0.1317    -0.1509     0.1786    -0.0739
            19       0.0019    -0.0090     0.0074    0.0370     -0.0050
            20       0.0235    -0.0139    -0.0159     0.0005    -0.0215
            21      -0.1220     0.0500    -0.2880    -0.1304     0.2082


                 Sum of Residuals              0
                 Sum of Squared Residuals       0.00282
                 Predicted Residual SS (PRESS)    0.00938



We find that there is a 16th and 17th observations have the ti value higher than the 3.29725.

LEVERAGE
       To test for x outliers the leverage of the hii values was calculated. By comparing hii to|DFFITS|>1 we
can identify possible x outliers. The leverage value is equal to . By examining all of the points only point
seven is near the leverage value but is not exceeding it, all other points are below the leverage point. The
leverage values are given in Table and 10th , 16th and 17th have X outliers which have |DFFITS| exceeding 1.




From the Residual V/S X1X4 plot we can observe a linear trend Hence we need to add the interaction term to
the Model . Hence Adding these terms and standardizing the models we can get the below plots and graphs .
    BONFERRONI TEST FOR OUTLIER:
                  From Figure 2, we identify the outlier as the 7th observation. It is a Y – outlier because it is in
            the Y – direction. Hence , we use Bonferroni outlier test for the outlier.
           Using the two tailed bonferroni test at α = 0.05, we have
           The Bonferroni critical value is given as,
               t(1-α/2n ; n-p-1 ) = t(1-.05/2×21 ; 21-5-1 ) = 3.286

                 From the SAS output , we have the test statistic as,
                                         Obs    t invt res     f inv50

                                         1       3.29725       0.90583
The REG Procedure
                                            Model: MO EL1
                                                      D
                                     Dependent Variable: yprime

                          Number of Observations Read                                         21
                          Number of Observations Used                                         21


                                          Analysis of Variance

                                                      Sum of                         Mean
  Source                           DF                Squares                       Square            F Value             Pr > F

  Model                             4                0.30425                  0.07606                  431.05            <.0001
  Error                            16                0.00282               0.00017646
  Corrected Total                  20                0.30707


                  Root MSE                           0.01328              R-Square               0.9908
                  Dependent Mean                     4.43447              Adj R-Sq               0.9885
                  Coeff Var                          0.29956


                                            Parameter Est imates

                        Parameter                    Standard                                                             Variance
Variable     DF          Est imate                      Error              t Value             Pr > | t |                In f l a t i on

Intercept     1          3.40999                     0.03197                 106.66                <.0001                             0
Runmin        1       0.00046190                  0.00001363                  33.88                <.0001                       1.13198
Down min      1       0.00047875                  0.00003234                  14.80                <.0001                       1.38942
Setupmin      1       0.00009967                  0.00002550                   3.91                0.0013                       1.00751
Effper        1          0.00641                  0.00034657                  18.51                <.0001                       1.33575




                                                 The REG Procedure
                                            Model: MO EL1
                                                      D
                                     Dependent Variable: yprime

                                              Output Stat is t i cs

                                                                  Hat Diag                      Cov
            Obs      Residual               RStudent                     H                    Ratio               DFFITS

             1        0.000243                  0.0185                0.0839                1.5071                0.0056
             2           0.0163                 1.3212                0.0962                0.8811                0.4310
             3        0.003302                  0.2515                0.0805                1.4705                0.0744
             4      - 0.004805                - 0.3892                0.1818                1.6050              - 0.1835
             5         - 0.0118               - 0.9941                0.1998                1.2544              - 0.4968
             6      - 0.004059                - 0.3671                0.3445                2.0145              - 0.2662
             7      - 0.002662                - 0.2058                0.1090                1.5281              - 0.0720
             8      - 0.002175                - 0.1791                0.2151                1.7405              - 0.0938
             9        0.002376                  0.1876                0.1465                1.5990                0.0777
            10        0.008857                  1.1031                0.6297                2.5247                1.4384
            11      - 0.004586                - 0.4284                0.3837                2.1084              - 0.3380
            12      - 0.004503                - 0.3548                0.1366                1.5339              - 0.1411
            13        0.001862                  0.1485                0.1635                1.6387                0.0657
            14           0.0161                 1.4161                0.2244                0.9507                0.7618
            15      - 0.000378                - 0.0287                0.0830                1.5054              - 0.0086
            16         - 0.0318               - 8.4950                0.5674                0.0005              - 9.7298
            17           0.0298                 3.6993                0.3415                0.0820                2.6641
            18      - 0.005207                - 0.4481                0.2731                1.7775              - 0.2747
            19        0.001193                  0.0970                0.1965                1.7130                0.0480
            20      - 0.001818                - 0.1385                0.0834                1.4968              - 0.0418
            21      - 0.006185                - 0.6212                0.4597                2.2511              - 0.5731

                                              Output Stat is t i cs

                     - - - - - - - - - - - - - - - - - - - - - - - - - DFBETAS- - - - - - - - - - - - - - - - - - - - - - - -
                                                                               -
            Obs      Intercept                     Runmin               Downmin       Setupmin                    Effper

              1         - 0.0026                0.0024                0.0020              - 0.0013                0.0023
              2           0.0890              - 0.1393                0.1299                0.0981              - 0.0646
              3         - 0.0136                0.0033                0.0208                0.0409                0.0076
              4           0.0886              - 0.0873              - 0.0899                0.1003              - 0.0737
              5           0.1991              - 0.0561                0.1258              - 0.1748              - 0.2414
              6           0.0798              - 0.1173              - 0.1672                0.1730              - 0.0436
7         0.0261     - 0.0022       0.0045     - 0.0379   - 0.0296
                       8         0.0175       0.0320       0.0334     - 0.0418   - 0.0415
                       9         0.0094       0.0395     - 0.0362     - 0.0071   - 0.0138
                      10         0.9167       0.5288     - 1.0356       0.0160   - 1.0440
                      11       - 0.2378     - 0.1161       0.0890       0.0114     0.3041
                      12         0.0378     - 0.0048       0.0316     - 0.0829   - 0.0447
                      13       - 0.0029     - 0.0130       0.0093       0.0506     0.0009
                      14         0.3462     - 0.6029     - 0.0053     - 0.0956   - 0.0817
                      15         0.0046     - 0.0012     - 0.0020     - 0.0018   - 0.0049
                      16       - 6.1126       7.5499       4.4954       4.1659     1.5784
                      17         0.4446     - 1.4287     - 0.6237     - 1.7983     0.7613




We see that observations 10,16 and 17 have absolute values greater than 1.
16:00 Saturday, December 6, 2008 135

                                                      The REG Procedure
                                                        Model: MO EL1
                                                                  D
                                                 Dependent Variable: yprime

                                                          Output Stat is t i cs

                                 - - - - - - - - - - - - - - - - - - - - - - - - - DFBETAS- - - - - - - - - - - - - - - - - - - - - - - -
                                                                                           -
                      Obs        Intercept                     Runmin               Downmin       Setupmin                    Effper

                       18             0.1043              - 0.1317              - 0.1509                0.1786              - 0.0739
                       19             0.0019              - 0.0090                0.0074                0.0370              - 0.0050
                       20             0.0235              - 0.0139              - 0.0159                0.0005              - 0.0215
                       21           - 0.1220                0.0500              - 0.2880              - 0.1304                0.2082


                                 Sum of Residuals                                                         0
                                 Sum of Squared Residuals                                           0.00282
                                 Predicted Residual SS (PRESS)                                      0.00938



We find that there is a 16th and 17th observations have the ti value higher than the 3.29725.

LEVERAGE
         To test for x outliers the leverage of the hii values was calculated. By comparing hii to|DFFITS|>1 we can
identify possible x outliers. The leverage value is equal to . By examining all of the points only point seven is near the
leverage value but is not exceeding it, all other points are below the leverage point. The leverage values are given in
Table and 10th , 16th and 17th have X outliers which have |DFFITS| exceeding 1.

Interaction and Partial Regression:
Below, the residuals vs. the residuals of the interactions terms are shown for each set of predictor variable bilinear
interaction terms. If the plot shows a linear or curvilinear trend it may suggest that that term needs to be included in the
model selection process. From the Figure we can see that the residuals plotted against the interaction of X1 and X2.
From figure, we observe that the points do have a set pattern i.e. they form a                 . Hence, we conclude that the
interaction term of X1 and X2 does significantly impact the model. The result of this is that it needs to be included as a
possible term in the model selection process.
                                                                The SAS System                        12:27 Wednesday, December 2, 1992                 85

                                                            The CORR Procedure

  11   Variables:     Cases         Runmin           Downmin Setupmin Effper                          x1x2            x1x3             x1x4     x2x3
                      x2x4          x3x4


                                                            Simple Stat is t i cs

       Variable             N                    Mean                Std Dev                          Sum               Minimum               Maximum

       Cases                21              28139                     6754                      590919                   11592                  36576
       Runmin               21          895.57384                231.80595                       18807               352.36668                   1260
       Down min             21          217.22857                108.26411                        4562                       0              492.80000
       Setupmin             21          207.25000                116.90431                        4352                       0              388.82000
       Effper               21           75.80000                  9.90571                        1592                54.00000               90.60000
       x1x2                 21             185305                   102699                     3891401                       0                 312136
       x1x3                 21             186914                    94604                     3925202                       0                 373047
       x1x4                 21              68455                    20823                     1437560                   24948                  96160
       x2x3                 21              45731                    38792                      960343                       0                 146376
       x2x4                 21              15970                     6706                      335367                       0                  26611
       x3x4                 21              15739                     9364                      330515                       0                  27888


                                        Pearson Correlat ion Coeff ic ients , N = 21

                        Cases                  Runmin                  Downmin                 Setupmin                     Effper               x1x2

       Cases          1.00000                0.85271                 - 0.12048                  0.02289                   0.58199             0.25666

       Runmin         0.85271                1.00000                 - 0.31922                 - 0.01174                  0.26098             0.29392
Downmin           - 0.12048     - 0.31922       1.00000         0.05890        - 0.48570     - 0.21515

Setupmin           0.02289      - 0.01174       0.05890         1.00000         0.02654       0.92742

Effper             0.58199       0.26098       - 0.48570        0.02654         1.00000       0.18734

x1x2               0.25666       0.29392       - 0.21515        0.92742         0.18734       1.00000

x1x3               0.35604       0.15644        0.84200       - 0.07242        - 0.22919     - 0.18400

x1x4               0.94699       0.90401       - 0.42237        0.01737         0.64029       0.32251

x2x3              - 0.24437     - 0.34795       0.66165         0.73111        - 0.39934      0.47990

x2x4               0.08254      - 0.22874       0.94610         0.01404        - 0.22875     - 0.22638

                              Pearson Correlat ion Coeff ic ients , N = 21

                              x1x3          x1x4           x2x3              x2x4          x3x4

         Cases            0.35604       0.94699        - 0.24437          0.08254      0.16147

         Runmin           0.15644       0.90401        - 0.34795      - 0.22874        0.06401
The SAS System         12:27 Wednesday, December 2, 1992        86

                                           The CORR Procedure

                           Pearson Correlat ion Coeff ic ients , N = 21

                           x1x3             x1x4           x2x3            x2x4              x3x4

       Downmin         0.84200        - 0.42237        0.66165         0.94610         - 0.10221

       Setupmin       - 0.07242        0.01737         0.73111         0.01404             0.96448

       Effper         - 0.22919        0.64029        - 0.39934       - 0.22875            0.27622

       x1x2           - 0.18400        0.32251         0.47990        - 0.22638            0.94632

       x1x3            1.00000         0.05837         0.37322         0.89412         - 0.15526

       x1x4            0.05837         1.00000        - 0.41554       - 0.24201            0.18346

       x2x3            0.37322        - 0.41554        1.00000         0.55003             0.56619

       x2x4            0.89412        - 0.24201        0.55003         1.00000         - 0.08268

                                            The SAS System         12:27 Wednesday, December 2, 1992        87

                                           The CORR Procedure

                           Pearson Correlat ion Coeff ic ients , N = 21

                  Cases           Runmin        Downmin         Setupmin          Effper             x1x2

x3x4             0.16147      0.06401          - 0.10221         0.96448      0.27622            0.94632

                           Pearson Correlat ion Coeff ic ients , N = 21

                           x1x3             x1x4           x2x3            x2x4              x3x4

       x3x4           - 0.15526        0.18346         0.56619        - 0.08268            1.00000
700

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                                                                                                                                                   0                                  100000                 200000   300000   400000
         0                      100000                        200000                         300000                         400000

                                                                 x1x2                                                                                                                                         x1x3




    700

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         20000         30000             40000              50000               60000            70000             80000               90000                100000

                                                                                x1x4




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                 0   10000     20000      30000          40000      50000        60000      70000        80000     90000          100000     110000         120000       130000    140000      150000

                                                                                                  x2x4



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                                                     0     10000        20000   30000    40000   50000     60000    70000      80000     90000         100000   110000   120000   130000   140000   150000

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                    0                           10000                            20000                        30000

                                                               x3x4




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                - 2000               - 1000                    0                         1000               2000

                                                         Re s i d u a l




         In order to measure the influence of the X1X4 variable on the plot , we perform the regression after
  adding X1X4 to the model .The results of the regressions are as follows :



                                                        The CORR Procedure

           6            Variables:            Cases      Runmin                Downmin Setupmin Effper                    stdx1x4


                                                        Simple Stat is t i cs

Variable                     N                 Mean                       Std Dev                   Sum               Minimum        Maximum

Cases                       21           28139                      6754                         590919                 11592           36576
Runmin                      21       895.57384                 231.80595                          18807            352.36668             1260
Downmin                     21       217.22857                 108.26411                           4562                     0       492.80000
Setupmin                    21       207.25000                 116.90431                           4352                     0       388.82000
Effper                      21        75.80000                   9.90571                           1592             54.00000         90.60000
stdx1x4                     21         0.24855                   0.90505                        5.21956             - 1.80919         2.63021


                                     Pearson Correlat ion Coeff ic ients , N = 21

                          Cases               Runmin                       Downmin              Setupmin                Effper        stdx1x4

Cases                   1.00000               0.85271                     - 0.12048              0.02289               0.58199       - 0.20520

Runmin                  0.85271               1.00000                     - 0.31922             - 0.01174              0.26098       - 0.51074

Downmin             - 0.12048            - 0.31922                         1.00000               0.05890              - 0.48570       0.54015

Setupmin                0.02289          - 0.01174                         0.05890               1.00000               0.02654        0.15996
Effper     0.58199     0.26098    - 0.48570   0.02654    1.00000    - 0.05965

stdx1x4   - 0.20520   - 0.51074    0.54015    0.15996   - 0.05965    1.00000
The SAS System         12:27 Wednesday, December 2, 1992       93

     Obs    Cases       Runmin    Downmin      Setupmin    Effper        stdx1          stdx2        stdx3

       1    33551       1027.17       222.3     177.12      80.6         0.56769        0.04684    - 0.25773
       2    24120        733.15       301.7     247.60      69.9       - 0.70069        0.78023      0.34515
       3    28800        885.47       257.1     292.37      75.6       - 0.04360        0.36828      0.72812
       4    36504       1094.37       249.8      93.90      81.5         0.85758        0.30085    - 0.96960
       5    34776       1061.37        89.8     288.82      90.6         0.71522      - 1.17702      0.69775
       6    35064       1071.67       348.1      20.27      74.1         0.75966        1.20882    - 1.59943
       7    31390        954.95       171.9     299.87      83.6         0.25615      - 0.41869      0.79227
       8    28008        846.90        99.1     314.05      88.8       - 0.20998      - 1.09111      0.91357
       9    33264       1159.02       101.0     180.00      79.2         1.13648      - 1.07357    - 0.23310
      10    27028       1259.98         0.0     180.00      64.4         1.57205      - 2.00647    - 0.23310
      11    22680       1019.83       240.0     180.00      54.0         0.53605        0.21033    - 0.23310
      12    31392        975.52       142.4     319.97      84.3         0.34487      - 0.69117      0.96421
      13    25992        782.85       270.6     373.48      74.0       - 0.48629        0.49297      1.42193
      14    17314        468.18       289.1     177.55      68.6       - 1.84374        0.66385    - 0.25405
      15    32327        963.37       205.6     242.85      83.0         0.29246      - 0.10741      0.30452
      16    11592        352.37       138.7      27.22      70.8       - 2.34337      - 0.72534    - 1.53998
      17    22104        660.32       134.0       0.00      83.5       - 1.01489      - 0.76875    - 1.77282
      18    36576       1108.13       291.9      39.98      78.4         0.91697        0.68972    - 1.43083
      19    24912        758.97       292.2     388.82      71.1       - 0.58932        0.69249      1.55315
      20    33509       1004.95       223.7     211.35      81.8         0.47184        0.05977      0.03507
      21    20016        618.53       492.8     297.03      54.0       - 1.19514        2.54536      0.76798

     Obs       stdx4       stdx1x2       stdx1x3     stdx1x4        stdx2x3       stdx2x4       stdx3x4

       1      0.48457       0.02659     - 0.14631     0.27508    - 0.01207         0.02270   - 0.12489
       2    - 0.59562     - 0.54670     - 0.24185     0.41734      0.26930       - 0.46472   - 0.20558
       3    - 0.02019     - 0.01606     - 0.03175     0.00088      0.26815       - 0.00744   - 0.01470
       4      0.57543       0.25801     - 0.83151     0.49348    - 0.29170         0.17312   - 0.55793
       5      1.49409     - 0.84183       0.49905     1.06861    - 0.82126       - 1.75857     1.04250
       6    - 0.17162       0.91829     - 1.21502   - 0.13037    - 1.93341       - 0.20745     0.27449
       7      0.78742     - 0.10724       0.20294     0.20170    - 0.33171       - 0.32968     0.62385
       8      1.31237       0.22911     - 0.19183   - 0.27557    - 0.99681       - 1.43195     1.19894
       9      0.34324     - 1.22009     - 0.26491     0.39008      0.25024       - 0.36849   - 0.08001
      10    - 1.15085     - 3.15426     - 0.36644   - 1.80919      0.46770         2.30915     0.26826
      11    - 2.20075       0.11275     - 0.12495   - 1.17971    - 0.04903       - 0.46289     0.51299
      12      0.85809     - 0.23836       0.33253     0.29593    - 0.66643       - 0.59308     0.82738
      13    - 0.18171     - 0.23973     - 0.69146     0.08836      0.70098       - 0.08958   - 0.25838
      14    - 0.72685     - 1.22397       0.46841     1.34013    - 0.16865       - 0.48252     0.18466
      15      0.72685     - 0.03141       0.08906     0.21257    - 0.03271       - 0.07807     0.22134
      16    - 0.50476       1.69975       3.60874     1.18284      1.1 1701        0.36612     0.77732
      17      0.77733       0.78020       1.79921   - 0.78890      1.36286       - 0.59758   - 1.37806
      18      0.26247       0.63245     - 1.31203     0.24068    - 0.98686         0.18103   - 0.37556
      19    - 0.47447     - 0.40809     - 0.91530     0.27962      1.07554       - 0.32857   - 0.73693
      20      0.60571       0.02820       0.01655     0.28580      0.00210         0.03621     0.02124
      21    - 2.20075     - 3.04206     - 0.91784     2.63021      1.95478       - 5.60171   - 1.69013




Model search:
Now we apply three search algorithms namely stepwise regression, backwards regression and best subset regression
algorithm. The criteria for model selection used to evaluate the possible models are higher R2, R2a; lower MSE, PRESS, as
well as lower number of predictor variables and Cp close to p. We have included the following variables in the model
search algorithms:Run_Min, Down_min, Schedule_min, eff_per, and other interaction terms. The model has been
standardized because the values of the predictor’s variables and response variable have varying magnitudes.


a. Selection process:

    The different procedures for model selection were done and the results were obtained . The resultsa for the
    different procedures are as follows :



    1: Best Sub Set model…..
First best set



                                                   The REG Procedure
                                                     Model: MO EL1
                                                               D
                                               Dependent Variable: Cases

                                           Adjusted R-Square Select ion Method

                                       Number of Observations Read             21
                                       Number of Observations Used             21



Number in       Adjusted
  Model         R-Square    R-Square        C(p)          AIC          SBC Variables in Model

       3         0.9951      0.9958       13.7203    262.2361     266.41422 Runmin Downmin Effper




   Second Best set :



       5         0.9969      0.9977       6.0000     254.1113     260.37839 Runmin Downmin Setupmin Effper




   The new Subset obtained are:

Dependent Variable: Cases

                                           Adjusted R-Square Select ion Method

                                       Number of Observations Read             21
                                       Number of Observations Used             21



  Number in      Adjusted
    Model        R-Square    R-Square         C(p)          AIC          SBC Variables in Model

            3       0.9951       0.9958     3.2091     262.2361    266.41422 Runmin Downmin Effper




           Similarly the other process of Backward deletion and Stepwise regression were carried out .The output is as
       follows :
                                                     The SAS System          12:27 Wednesday, December 2, 1992 105

                                                   The REG Procedure
                                                     Model: MO EL1
                                                               D
                                               Dependent Variable: Cases

                                       Number of Observations Read             21
                                       Number of Observations Used             21

                                               Stepwise Select ion: Step 1


                           Variable Runmin Entered: R-Square = 0.7271 and C(p) = 1732.637
Analysis of Variance

                                                  Sum of                Mean
            Source                   DF          Squares              Square     F Value        Pr > F

            Model                     1        663351807        663351807          50.63        <.0001
            Error                    19        248945175         13102378
            Corrected Total          20        912296982


                               Parameter       Standard
                  Variable      Est imate         Error    Type I I   SS F Value       Pr > F

                  Intercept   5888.80747     3225.28395      43678620           3.33   0.0836
                  Runmin        24.84462        3.49169     663351807          50.63   <.0001

                                   Bounds on condit ion number: 1, 1
------------------------------------------------------------------------------------------------------

                                      Stepwise Select ion: Step 2


                     Variable Effper Entered: R-Square = 0.8658 and C(p) = 845.6608


                                            Analysis of Variance

                                                  Sum of                Mean
            Source                   DF          Squares              Square     F Value        Pr > F

            Model                     2        789838790        394919395          58.05        <.0001
            Error                    18        122458192          6803233
            Corrected Total          20        912296982
The SAS System           12:27 Wednesday, December 2, 1992 106

                                          The REG Procedure
                                            Model: MO EL1
                                                      D
                                      Dependent Variable: Cases

                                      Stepwise Select ion: Step 2

                               Parameter       Standard
                  Variable      Est imate         Error    Type I I   SS F Value       Pr > F

                  Intercept       - 11419    4638.30362      41235217           6.06   0.0241
                  Runmin        21.91167        2.60637     480833856          70.68   <.0001
                  Effper       262.99050       60.99227     126486982          18.59   0.0004

                              Bounds on condit ion number: 1.0731, 4.2923
------------------------------------------------------------------------------------------------------

                                      Stepwise Select ion: Step 3


                     Variable Downmin Entered: R-Square = 0.9958 and C(p) = 13.7203


                                            Analysis of Variance

                                                  Sum of                Mean
            Source                   DF          Squares              Square     F Value        Pr > F

            Model                     3        908495108        302831703        1354.11        <.0001
            Error                    17          3801874           223640
            Corrected Total          20        912296982


                               Parameter       Standard
                  Variable      Est imate         Error    Type I I   SS F Value       Pr > F

                  Intercept       - 28901    1132.80996     145571123  650.92          <.0001
                  Runmin        24.46158        0.48535     568081327 2540.16          <.0001
                  Down min      26.43461        1.14763     118656318  530.57          <.0001
                  Effper       387.74395       12.31346     221757766  991.59          <.0001

                              Bounds on condit ion number: 1.3806, 11 .529
------------------------------------------------------------------------------------------------------

                                      Stepwise Select ion: Step 4


                     Variable stdx1x4 Entered: R-Square = 0.9975 and C(p) = 5.2554
The SAS System             12:27 Wednesday, December 2, 1992 107

                                                The REG Procedure
                                                  Model: MO EL1
                                                            D
                                            Dependent Variable: Cases

                                            Stepwise Select ion: Step 4

                                                  Analysis of Variance

                                                        Sum of                  Mean
              Source                       DF          Squares                Square    F Value        Pr > F

              Model                         4        909984098          227496024       1573.77        <.0001
              Error                        16          2312884             144555
              Corrected Total              20        912296982


                                     Parameter       Standard
                     Variable         Est imate         Error      Type I I   SS F Value      Pr > F

                     Intercept          - 28237     933.96796       132134456 914.08          <.0001
                     Runmin           25.15032        0.44533       461068290 3189.56         <.0001
                     Down min         24.42755        1.1 1462       69428305 480.29          <.0001
                     Effper          375.20126       10.64318       179646862 1242.76         <.0001
                     stdx1x4         425.29879      132.51505         1488990   10.30         0.0055

                              Bounds on condit ion number: 2.0148, 28.068
------------------------------------------------------------------------------------------------------


                   Al l var iables le f t in the model are signi f i cant at the 0.1000 level .

              No other var iable met the 0.1000 signi f i cance level for entry in to the model.



                                          Summary of Stepwise Select ion

          Variable        Variable        Number       Part ia l       Model
  Step    Entered         Removed         Vars In      R-Square       R-Square         C(p)       F Value       Pr > F

    1     Runmin                                1       0.7271          0.7271         1732.64      50.63       <.0001
    2     Effper                                2       0.1386          0.8658         845.661      18.59       0.0004
    3     Downmin                               3       0.1301          0.9958         13.7203     530.57       <.0001
    4     stdx1x4                               4       0.0016          0.9975          5.2554      10.30       0.0055




To find out the outliers , we use the below terms :

Run_min ,down_min,eff_per (std x1,x4)

F*=MSR/MSE=302831703

F*=1354.103

Run_min:1000

Down_min: 250

Eff_per: 90

From Annova Table
Run_min,Down_min,Eff_per

X=2P/n=2*4/21=0.38095

Obsv10 =hii=.6296

     16= hii= 0.4634

    21= hii=.4359

Finv=3.297 No Youtliers




Conclusion

The conclusion of this analysis is The water line at America's Beverage Company (Kroger Manufacturing) is
the main source of income for the manufacturing plant and the number of cases of water produced during the
month of October was 591,092. Also, there are three (3) more soft drinks lines, which are not returning the
pertinent dividends because of marketing purposes but increasing costs of production for the facility. At this
point, it is imperative to maximize the number of water cases processed in the water line in order to keep the
plant running and justify any capital appropriation requested to the General Office.



In our final model the response variable has a linear correlation with the predictor variables.

The final MLR model form is reasonable. The final model satisfied all the model assumptions and has constant
variance, normality is OK, multicollinearity problem is eliminated.

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Statistics project2

  • 1. Advanced Engineering Statistics -Multiple Linear Regression Project 2 Instructor: Dr.Victoria Chen Group Members : Rakesh Raj. N Jaime Sanguino Shriraam Madanagopal
  • 2. Introduction to Multiple Linear Regressions: The Multiple Linear Regression is to learn more about the relationship between several independent or predictor variables and a dependent or criterion variable. The Objective of this project is to develop a best multiple linear regression model for the response variable and the Regressors (set of predictor variables). A statistical technique that uses several explanatory variables to predict the outcome of a response variable. The goal of multiple linear regressions (MLR) is to model the relationship between the explanatory and response variables. The model for MLR, given n observations, is: yi = B0 + B1xi1 + B2xi2 + ... + Bpxip + Ei where i = 1, 2, n MLR takes a group of random variables and tries to find a mathematical relationship between them. The model creates a relationship in the form of a straight line (linear) that best approximates all the individual data points. MLR is often used to determine how many specific factors such as, the price of a commodity, interest rates, and particular industries or sectors, influence the price movement of an asset. For example, the current price of oil, lending rates, and the price movement of oil futures, can all have an effect on the price of an oil company's stock price. MLR could be used to model the impact that each of these variables have on stock's price. Our Project: The water line at America’s Beverage Company (Kroger Manufacturing) is the main source of income for the manufacturing plant and the number of cases of water produced during the month of October was 591,092. Also, there are three (3) more soft drinks lines, which are not returning the pertinent dividends because of marketing purposes but increasing costs of production for the facility. At this point, it is imperative to maximize the number of water cases processed in the water line in order to keep the plant running and justify any capital appropriation requested to the General Office. Industrial Engineering concepts suggest that the minimization of downtime scheduled, not scheduled downtime and set up time and the maximization of the running time and efficiency of the equipment. Achieving these objectives will allow the enhancement of profits generated from the automated water line. DISCUSSION: Modeling as dependent variable the number the water cases produced in the line y= number of water cases and using the predictors run time, downtime, unscheduled down time and setup time will be have the following variables X1: Run time, the time where the line is processing the product. X2: Downtime, the time where preventive maintenance is used to check the performance of the equipment and execute any repairs if necessary. X3: Setup time, the time used to do changes on the equipment when size of bottles change.
  • 3. X4: Efficiency, the key performance indicator used by management in order to check status of production. Data Set: Cases(Y) Runmin(X1) Downmin(X2) Setupmin(X3) Effper(X4) 33,551.0 1,027.2 222.3 177.12 80.6 24,120.0 733.2 301.7 247.60 69.9 28,800.0 885.5 257.1 292.37 75.6 36,504.0 1,094.4 249.8 93.90 81.5 34,776.0 1,061.4 89.8 288.82 90.6 35,064.0 1,071.7 348.1 20.27 74.1 31,390.0 955.0 171.9 299.87 83.6 28,008.0 846.9 99.1 314.05 88.8 33,264.0 1,159.0 101.0 180.00 79.2 27,028.0 1,260.0 0.0 180.00 64.4 22,680.0 1,019.8 240.0 180.00 54.0 31,392.0 975.5 142.4 319.97 84.3 25,992.0 782.9 270.6 373.48 74.0 17,314.0 468.2 289.1 177.55 68.6 32,327.0 963.4 205.6 242.85 83.0 11,592.0 352.4 138.7 27.22 70.8 22,104.0 660.3 134.0 0.00 83.5 173.0 5.2 0.0 0.00 99.2 36,576.0 1,108.1 291.9 39.98 78.4 24,912.0 759.0 292.2 388.82 71.1 33,509.0 1,005.0 223.7 211.35 81.8 20,016.0 618.5 492.8 297.03 54.0
  • 4. As we were suggested by Dr. Chen to choose between the Not Scheduled and Down_min , we opted for Down_min and continued with the analysis of the project. A Methodical approach to our Project: In our project we have 4 predictors, the preliminary model is as mentioned below: Yi = β0 + β1 xi1 + β2 xi2 + β3 xi3 + β4 xi4 + εi i = 1,..., n observations X1: Run time, the time where the line is processing the product.
  • 5. X2: Downtime, the time where preventive maintenance is used to check the performance of the equipment and execute any repairs if necessary. X3: Setup time, the time used to do changes on the equipment when size of bottles change. X4: Efficiency, the key performance indicator used by management in order to check status of production. From the graph attached above, we can observe the different relations between the predictors and the response variables, as well as the relationship between the predictors. In the above figure we find that there in no major trend present in the X2, X3 and X5(Since we have omitted the consideration of X4 ie:- NOT SCHEDULED,we should check the co-relation of X5). The correlation between the predictor and response variable appear to be pretty good having a linear trend. The Predictor- Predictor plots show a pretty good scatter apart from the X1 and X4 plot. The ANOVA table below shows the various correlations between the Predictors and the response variable . The highest correlation gives us a value of 0.85271 which indicates that the effect of Runmin has the highest influence on the Response variable. The CORR Procedure 5 Variables: Cases Runmin Downmin Setupmin Effper Simple Statistics Variable N Mean Std Dev Sum Minimum Maximum Label Cases 22 26868 8888 591092 173.00000 36576 Cases Runmin 22 855.10381 295.30889 18812 5.23333 1260 Runmin Downmin 22 207.34846 115.36229 4562 0 492.81662 Downmin Setupmin 22 197.82879 122.34451 4352 0 388.81667 Setupmin Effper 22 76.86493 10.87210 1691 54.01255 99.18188 Effper Pearson Correlation Coefficients, N = 22 Cases Runmin Downmin Setupmin Effper Cases 1.00000 0.91564 0.18742 0.25811 0.07561 Runmin 0.91564 1.00000 0.03402 0.22376 -0.11767 Downmin 0.18742 0.03402 1.00000 0.19526 -0.57898 Setupmin 0.25811 0.22376 0.19526 1.00000 -0.14302 Effper 0.07561 -0.11767 -0.57898 -0.14302 1.00000
  • 6. Our preliminary analysis suggests that bivariate relationships between the individual factors should not cause a problem in our model so the assumptions of the model need to be evaluated to further appropriateness of our whole model. Model Adequacy: The residual analysis is used to verify our model assumptions: 1. The current MLR Model is reasonable 2. The residuals have constant variance 3. The residuals are normally distributed 4. The residuals are uncorrelated 5. No outliers 6. The predictors are not highly correlated with each other. Residuals vs. fitted values: Our preliminary fitted model is a first order four variable Linear Equation of the form as shown below, Y i = b0 + b1 xi + b2x2 + b3x3 + b4x4 + ε .i ^ Cases = -28850 -24.46143* Runmin - 26.47767*Downmin -0.42515 Setup time + 388.10655 Effper Residual V/S Fitted Value: The residuals given by (e) represent the difference between the model and fitted values of the cases. This comparison is useful for identifying possible outliers, checking the general form of the model and checking for constancy of the variance of error terms. The plot of residuals vs. the fitted values is as shown below in figure. Inference: A Funnel shape can be observed in the values between the Residual and the Fitted values. This indicates that Constant –Variance is NOT OK . Hence we need to proceed with the transformation on Y , we use a Square root transformation to check if the Non-Constant Variance can be improved.
  • 7. Residuals vs. Predictor variables: 1 : Residuals V/S Predictors plots are as given in figures below, The graph’s above indicate the relationship between the Residuals and the various Predictors of the Model. We can observe a random scatter in all the plots. Since there is no curvature we can state that the current MLR model forms are OK. Normal probability plot: The plot between residuals and normal scores is as shown below.From the graph we observe a Line which is not Straight . Hence the Normality is NOT OK .
  • 8. Plots for Predictor - Predictor variables Below are the plots between Runmin, Downtime, Setupmin and EffPer.
  • 10. From above plots we can observe a proper Scatter and there is no trend or curvature in the plots are randomly scattered with our Predictor Vs Predictor Variables. Transformation: A Funnel can be observed in the plot between Residual and Yhat .Hence As suggested by Dr Chen , we carried out a Square root of “Y “ transformation . The results are as given below….Since there was not much of an improvement which was observed . We reverted back to the old data set without any Transformations . The values of these are as follows : Formal tests on constancy of variance, multi co linearity, normality of error terms, lack of fit and X or Y outliers. i. Test for normality: We conduct a correlation test for normality with value of α=.05. From the SAS output, we have the coefficient of correlation is given as 0.9263 And from the given α=0.05, the test statistic we have from table B6 from the textbook is 0.9525. Decision rule is as given below H0: Normality is OK H1: Normality is violated If ρ ( e, z ) < c( α , n ) (Table B6) Reject H0 ˆ Since ρ ( e, z ) = 0.9263 ≤ c( 0.05,21) = 0.9525 ⇒ Normality is Ok. ˆ
  • 11. The CORR Procedure 2 Variables: e2 enrm Simple Statistics Variable N Mean Std Dev Sum Minimum Maximum Label e2 21 0 0.01188 0 -0.03180 0.02978 Residual enrm 21 0 0.96464 0 -1.88951 1.88951 Normal Scores Pearson Correlation Coefficients, N = 21 Prob > |r| under H0: Rho=0 e2 enrm e2 1.00000 0.92630 Residual <.0001 enrm 0.92630 1.00000 Normal Scores <.000 Test For Multicollinearity: The variance inflation factors associated with various predictor variables are as given below, VIFrunmin= (1-Rrunmin2)-1 = 1.13198 VIFdowntime = (1-Rdowntime2)-1 = 1.38942 VIFsetuptime = (1-Rsetuptime2)-1 = 1.00751 VIFEffper = (1-Reffper 2)-1 = 1.33575 VIF bar= 1.216165 < 5 The result of the above VIF values is that it confirms there is little multicollinearity among the individual predictor variables. A VIF value near or above 5 would indicate a serious deviation in the variance i.e. serious multicollinearity but a perfect VIF value would be 1 which all of our variables are relatively close. The maximum value of 1.38942 for focal length being used as an indicator the total model confirms that multicollinearity is not present as suggested by earlier plots. BONFERRONI TEST FOR OUTLIER: From Figure 2, we identify the outlier as the 7th observation. It is a Y – outlier because it is in the Y – direction. Hence , we use Bonferroni outlier test for the outlier. Using the two tailed bonferroni test at α = 0.05, we have The Bonferroni critical value is given as, t(1-α/2n ; n-p-1 ) = t(1-.05/2×21 ; 21-5-1 ) = 3.286 From the SAS output , we have the test statistic as, Obs tinvtres finv50
  • 12. 1 3.29725 0.90583
  • 13. The REG Procedure Model: MODEL1 Dependent Variable: yprime Number of Observations Read 21 Number of Observations Used 21 Analysis of Variance Sum of Mean Source DF Squares Square F Value Pr > F Model 4 0.30425 0.07606 431.05 <.0001 Error 16 0.00282 0.00017646 Corrected Total 20 0.30707 Root MSE 0.01328 R-Square 0.9908 Dependent Mean 4.43447 Adj R-Sq 0.9885 Coeff Var 0.29956 Parameter Estimates Parameter Standard Variance Variable DF Estimate Error t Value Pr > |t| Inflation Intercept 1 3.40999 0.03197 106.66 <.0001 0 Runmin 1 0.00046190 0.00001363 33.88 <.0001 1.13198 Downmin 1 0.00047875 0.00003234 14.80 <.0001 1.38942 Setupmin 1 0.00009967 0.00002550 3.91 0.0013 1.00751 Effper 1 0.00641 0.00034657 18.51 <.0001 1.33575 The REG Procedure Model: MODEL1 Dependent Variable: yprime Output Statistics Hat Diag Cov Obs Residual RStudent H Ratio DFFITS 1 0.000243 0.0185 0.0839 1.5071 0.0056 2 0.0163 1.3212 0.0962 0.8811 0.4310 3 0.003302 0.2515 0.0805 1.4705 0.0744 4 -0.004805 -0.3892 0.1818 1.6050 -0.1835 5 -0.0118 -0.9941 0.1998 1.2544 -0.4968 6 -0.004059 -0.3671 0.3445 2.0145 -0.2662
  • 14. 7 -0.002662 -0.2058 0.1090 1.5281 -0.0720 8 -0.002175 -0.1791 0.2151 1.7405 -0.0938 9 0.002376 0.1876 0.1465 1.5990 0.0777 10 0.008857 1.1031 0.6297 2.5247 1.4384 11 -0.004586 -0.4284 0.3837 2.1084 -0.3380 12 -0.004503 -0.3548 0.1366 1.5339 -0.1411 13 0.001862 0.1485 0.1635 1.6387 0.0657 14 0.0161 1.4161 0.2244 0.9507 0.7618 15 -0.000378 -0.0287 0.0830 1.5054 -0.0086 16 -0.0318 -8.4950 0.5674 0.0005 -9.7298 17 0.0298 3.6993 0.3415 0.0820 2.6641 18 -0.005207 -0.4481 0.2731 1.7775 -0.2747 19 0.001193 0.0970 0.1965 1.7130 0.0480 20 -0.001818 -0.1385 0.0834 1.4968 -0.0418 21 -0.006185 -0.6212 0.4597 2.2511 -0.5731 Output Statistics -------------------------DFBETAS------------------------- Obs Intercept Runmin Downmin Setupmin Effper 1 -0.0026 0.0024 0.0020 -0.0013 0.0023 2 0.0890 -0.1393 0.1299 0.0981 -0.0646 3 -0.0136 0.0033 0.0208 0.0409 0.0076 4 0.0886 -0.0873 -0.0899 0.1003 -0.0737 5 0.1991 -0.0561 0.1258 -0.1748 -0.2414 6 0.0798 -0.1173 -0.1672 0.1730 -0.0436 7 0.0261 -0.0022 0.0045 -0.0379 -0.0296 8 0.0175 0.0320 0.0334 -0.0418 -0.0415 9 0.0094 0.0395 -0.0362 -0.0071 -0.0138 10 0.9167 0.5288 -1.0356 0.0160 -1.0440 11 -0.2378 -0.1161 0.0890 0.0114 0.3041 12 0.0378 -0.0048 0.0316 -0.0829 -0.0447 13 -0.0029 -0.0130 0.0093 0.0506 0.0009 14 0.3462 -0.6029 -0.0053 -0.0956 -0.0817 15 0.0046 -0.0012 -0.0020 -0.0018 -0.0049 16 -6.1126 7.5499 4.4954 4.1659 1.5784 17 0.4446 -1.4287 -0.6237 -1.7983 0.7613 We see that observations 10,16 and 17 have absolute values greater than 1. We measure the value with respect to 1 since the data set is less than 30 values.
  • 15. 16:00 Saturday, December 6, 2008 135 The REG Procedure Model: MODEL1 Dependent Variable: yprime Output Statistics -------------------------DFBETAS------------------------- Obs Intercept Runmin Downmin Setupmin Effper 18 0.1043 -0.1317 -0.1509 0.1786 -0.0739 19 0.0019 -0.0090 0.0074 0.0370 -0.0050 20 0.0235 -0.0139 -0.0159 0.0005 -0.0215 21 -0.1220 0.0500 -0.2880 -0.1304 0.2082 Sum of Residuals 0 Sum of Squared Residuals 0.00282 Predicted Residual SS (PRESS) 0.00938 We find that there is a 16th and 17th observations have the ti value higher than the 3.29725. LEVERAGE To test for x outliers the leverage of the hii values was calculated. By comparing hii to|DFFITS|>1 we can identify possible x outliers. The leverage value is equal to . By examining all of the points only point seven is near the leverage value but is not exceeding it, all other points are below the leverage point. The leverage values are given in Table and 10th , 16th and 17th have X outliers which have |DFFITS| exceeding 1. From the Residual V/S X1X4 plot we can observe a linear trend Hence we need to add the interaction term to the Model . Hence Adding these terms and standardizing the models we can get the below plots and graphs . BONFERRONI TEST FOR OUTLIER: From Figure 2, we identify the outlier as the 7th observation. It is a Y – outlier because it is in the Y – direction. Hence , we use Bonferroni outlier test for the outlier. Using the two tailed bonferroni test at α = 0.05, we have The Bonferroni critical value is given as, t(1-α/2n ; n-p-1 ) = t(1-.05/2×21 ; 21-5-1 ) = 3.286 From the SAS output , we have the test statistic as, Obs t invt res f inv50 1 3.29725 0.90583
  • 16. The REG Procedure Model: MO EL1 D Dependent Variable: yprime Number of Observations Read 21 Number of Observations Used 21 Analysis of Variance Sum of Mean Source DF Squares Square F Value Pr > F Model 4 0.30425 0.07606 431.05 <.0001 Error 16 0.00282 0.00017646 Corrected Total 20 0.30707 Root MSE 0.01328 R-Square 0.9908 Dependent Mean 4.43447 Adj R-Sq 0.9885 Coeff Var 0.29956 Parameter Est imates Parameter Standard Variance Variable DF Est imate Error t Value Pr > | t | In f l a t i on Intercept 1 3.40999 0.03197 106.66 <.0001 0 Runmin 1 0.00046190 0.00001363 33.88 <.0001 1.13198 Down min 1 0.00047875 0.00003234 14.80 <.0001 1.38942 Setupmin 1 0.00009967 0.00002550 3.91 0.0013 1.00751 Effper 1 0.00641 0.00034657 18.51 <.0001 1.33575 The REG Procedure Model: MO EL1 D Dependent Variable: yprime Output Stat is t i cs Hat Diag Cov Obs Residual RStudent H Ratio DFFITS 1 0.000243 0.0185 0.0839 1.5071 0.0056 2 0.0163 1.3212 0.0962 0.8811 0.4310 3 0.003302 0.2515 0.0805 1.4705 0.0744 4 - 0.004805 - 0.3892 0.1818 1.6050 - 0.1835 5 - 0.0118 - 0.9941 0.1998 1.2544 - 0.4968 6 - 0.004059 - 0.3671 0.3445 2.0145 - 0.2662 7 - 0.002662 - 0.2058 0.1090 1.5281 - 0.0720 8 - 0.002175 - 0.1791 0.2151 1.7405 - 0.0938 9 0.002376 0.1876 0.1465 1.5990 0.0777 10 0.008857 1.1031 0.6297 2.5247 1.4384 11 - 0.004586 - 0.4284 0.3837 2.1084 - 0.3380 12 - 0.004503 - 0.3548 0.1366 1.5339 - 0.1411 13 0.001862 0.1485 0.1635 1.6387 0.0657 14 0.0161 1.4161 0.2244 0.9507 0.7618 15 - 0.000378 - 0.0287 0.0830 1.5054 - 0.0086 16 - 0.0318 - 8.4950 0.5674 0.0005 - 9.7298 17 0.0298 3.6993 0.3415 0.0820 2.6641 18 - 0.005207 - 0.4481 0.2731 1.7775 - 0.2747 19 0.001193 0.0970 0.1965 1.7130 0.0480 20 - 0.001818 - 0.1385 0.0834 1.4968 - 0.0418 21 - 0.006185 - 0.6212 0.4597 2.2511 - 0.5731 Output Stat is t i cs - - - - - - - - - - - - - - - - - - - - - - - - - DFBETAS- - - - - - - - - - - - - - - - - - - - - - - - - Obs Intercept Runmin Downmin Setupmin Effper 1 - 0.0026 0.0024 0.0020 - 0.0013 0.0023 2 0.0890 - 0.1393 0.1299 0.0981 - 0.0646 3 - 0.0136 0.0033 0.0208 0.0409 0.0076 4 0.0886 - 0.0873 - 0.0899 0.1003 - 0.0737 5 0.1991 - 0.0561 0.1258 - 0.1748 - 0.2414 6 0.0798 - 0.1173 - 0.1672 0.1730 - 0.0436
  • 17. 7 0.0261 - 0.0022 0.0045 - 0.0379 - 0.0296 8 0.0175 0.0320 0.0334 - 0.0418 - 0.0415 9 0.0094 0.0395 - 0.0362 - 0.0071 - 0.0138 10 0.9167 0.5288 - 1.0356 0.0160 - 1.0440 11 - 0.2378 - 0.1161 0.0890 0.0114 0.3041 12 0.0378 - 0.0048 0.0316 - 0.0829 - 0.0447 13 - 0.0029 - 0.0130 0.0093 0.0506 0.0009 14 0.3462 - 0.6029 - 0.0053 - 0.0956 - 0.0817 15 0.0046 - 0.0012 - 0.0020 - 0.0018 - 0.0049 16 - 6.1126 7.5499 4.4954 4.1659 1.5784 17 0.4446 - 1.4287 - 0.6237 - 1.7983 0.7613 We see that observations 10,16 and 17 have absolute values greater than 1.
  • 18. 16:00 Saturday, December 6, 2008 135 The REG Procedure Model: MO EL1 D Dependent Variable: yprime Output Stat is t i cs - - - - - - - - - - - - - - - - - - - - - - - - - DFBETAS- - - - - - - - - - - - - - - - - - - - - - - - - Obs Intercept Runmin Downmin Setupmin Effper 18 0.1043 - 0.1317 - 0.1509 0.1786 - 0.0739 19 0.0019 - 0.0090 0.0074 0.0370 - 0.0050 20 0.0235 - 0.0139 - 0.0159 0.0005 - 0.0215 21 - 0.1220 0.0500 - 0.2880 - 0.1304 0.2082 Sum of Residuals 0 Sum of Squared Residuals 0.00282 Predicted Residual SS (PRESS) 0.00938 We find that there is a 16th and 17th observations have the ti value higher than the 3.29725. LEVERAGE To test for x outliers the leverage of the hii values was calculated. By comparing hii to|DFFITS|>1 we can identify possible x outliers. The leverage value is equal to . By examining all of the points only point seven is near the leverage value but is not exceeding it, all other points are below the leverage point. The leverage values are given in Table and 10th , 16th and 17th have X outliers which have |DFFITS| exceeding 1. Interaction and Partial Regression: Below, the residuals vs. the residuals of the interactions terms are shown for each set of predictor variable bilinear interaction terms. If the plot shows a linear or curvilinear trend it may suggest that that term needs to be included in the model selection process. From the Figure we can see that the residuals plotted against the interaction of X1 and X2. From figure, we observe that the points do have a set pattern i.e. they form a . Hence, we conclude that the interaction term of X1 and X2 does significantly impact the model. The result of this is that it needs to be included as a possible term in the model selection process. The SAS System 12:27 Wednesday, December 2, 1992 85 The CORR Procedure 11 Variables: Cases Runmin Downmin Setupmin Effper x1x2 x1x3 x1x4 x2x3 x2x4 x3x4 Simple Stat is t i cs Variable N Mean Std Dev Sum Minimum Maximum Cases 21 28139 6754 590919 11592 36576 Runmin 21 895.57384 231.80595 18807 352.36668 1260 Down min 21 217.22857 108.26411 4562 0 492.80000 Setupmin 21 207.25000 116.90431 4352 0 388.82000 Effper 21 75.80000 9.90571 1592 54.00000 90.60000 x1x2 21 185305 102699 3891401 0 312136 x1x3 21 186914 94604 3925202 0 373047 x1x4 21 68455 20823 1437560 24948 96160 x2x3 21 45731 38792 960343 0 146376 x2x4 21 15970 6706 335367 0 26611 x3x4 21 15739 9364 330515 0 27888 Pearson Correlat ion Coeff ic ients , N = 21 Cases Runmin Downmin Setupmin Effper x1x2 Cases 1.00000 0.85271 - 0.12048 0.02289 0.58199 0.25666 Runmin 0.85271 1.00000 - 0.31922 - 0.01174 0.26098 0.29392
  • 19. Downmin - 0.12048 - 0.31922 1.00000 0.05890 - 0.48570 - 0.21515 Setupmin 0.02289 - 0.01174 0.05890 1.00000 0.02654 0.92742 Effper 0.58199 0.26098 - 0.48570 0.02654 1.00000 0.18734 x1x2 0.25666 0.29392 - 0.21515 0.92742 0.18734 1.00000 x1x3 0.35604 0.15644 0.84200 - 0.07242 - 0.22919 - 0.18400 x1x4 0.94699 0.90401 - 0.42237 0.01737 0.64029 0.32251 x2x3 - 0.24437 - 0.34795 0.66165 0.73111 - 0.39934 0.47990 x2x4 0.08254 - 0.22874 0.94610 0.01404 - 0.22875 - 0.22638 Pearson Correlat ion Coeff ic ients , N = 21 x1x3 x1x4 x2x3 x2x4 x3x4 Cases 0.35604 0.94699 - 0.24437 0.08254 0.16147 Runmin 0.15644 0.90401 - 0.34795 - 0.22874 0.06401
  • 20. The SAS System 12:27 Wednesday, December 2, 1992 86 The CORR Procedure Pearson Correlat ion Coeff ic ients , N = 21 x1x3 x1x4 x2x3 x2x4 x3x4 Downmin 0.84200 - 0.42237 0.66165 0.94610 - 0.10221 Setupmin - 0.07242 0.01737 0.73111 0.01404 0.96448 Effper - 0.22919 0.64029 - 0.39934 - 0.22875 0.27622 x1x2 - 0.18400 0.32251 0.47990 - 0.22638 0.94632 x1x3 1.00000 0.05837 0.37322 0.89412 - 0.15526 x1x4 0.05837 1.00000 - 0.41554 - 0.24201 0.18346 x2x3 0.37322 - 0.41554 1.00000 0.55003 0.56619 x2x4 0.89412 - 0.24201 0.55003 1.00000 - 0.08268 The SAS System 12:27 Wednesday, December 2, 1992 87 The CORR Procedure Pearson Correlat ion Coeff ic ients , N = 21 Cases Runmin Downmin Setupmin Effper x1x2 x3x4 0.16147 0.06401 - 0.10221 0.96448 0.27622 0.94632 Pearson Correlat ion Coeff ic ients , N = 21 x1x3 x1x4 x2x3 x2x4 x3x4 x3x4 - 0.15526 0.18346 0.56619 - 0.08268 1.00000
  • 21. 700 600 500 400 300 700 200 600 100 500 400 0 300 - 100 200 - 200 100 - 300 0 - 100 - 400 - 200 - 500 - 300 - 600 - 400 - 500 - 700 - 600 - 800 - 700 - 900 - 800 - 1000 - 900 - 1000 - 1100 - 1100 - 1200 - 1200 0 100000 200000 300000 400000 0 100000 200000 300000 400000 x1x2 x1x3 700 600 500 400 300 200 100 0 - 100 - 200 - 300 - 400 - 500 - 600 - 700 - 800 - 900 - 1000 - 1100 - 1200 20000 30000 40000 50000 60000 70000 80000 90000 100000 x1x4 700 600 500 400 300 200 100 0 - 100 - 200 - 300 - 400 - 500 - 600 - 700 - 800 - 900 - 1000 - 1100 - 1200 0 10000 20000 30000 40000 50000 60000 70000 80000 90000 100000 110000 120000 130000 140000 150000 x2x4 700 600 500 400 300 200 100 0 - 100 - 200 - 300 - 400 - 500 - 600 - 700 - 800 - 900 - 1000 - 1100 - 1200 0 10000 20000 30000 40000 50000 60000 70000 80000 90000 100000 110000 120000 130000 140000 150000 x2x3
  • 22. 700 600 500 400 300 200 100 0 - 100 - 200 - 300 - 400 - 500 - 600 - 700 - 800 - 900 - 1000 - 1100 - 1200 0 10000 20000 30000 x3x4 700 600 500 400 300 200 100 0 - 100 - 200 - 300 - 400 - 500 - 600 - 700 - 800 - 900 - 1000 - 1100 - 1200 - 2000 - 1000 0 1000 2000 Re s i d u a l In order to measure the influence of the X1X4 variable on the plot , we perform the regression after adding X1X4 to the model .The results of the regressions are as follows : The CORR Procedure 6 Variables: Cases Runmin Downmin Setupmin Effper stdx1x4 Simple Stat is t i cs Variable N Mean Std Dev Sum Minimum Maximum Cases 21 28139 6754 590919 11592 36576 Runmin 21 895.57384 231.80595 18807 352.36668 1260 Downmin 21 217.22857 108.26411 4562 0 492.80000 Setupmin 21 207.25000 116.90431 4352 0 388.82000 Effper 21 75.80000 9.90571 1592 54.00000 90.60000 stdx1x4 21 0.24855 0.90505 5.21956 - 1.80919 2.63021 Pearson Correlat ion Coeff ic ients , N = 21 Cases Runmin Downmin Setupmin Effper stdx1x4 Cases 1.00000 0.85271 - 0.12048 0.02289 0.58199 - 0.20520 Runmin 0.85271 1.00000 - 0.31922 - 0.01174 0.26098 - 0.51074 Downmin - 0.12048 - 0.31922 1.00000 0.05890 - 0.48570 0.54015 Setupmin 0.02289 - 0.01174 0.05890 1.00000 0.02654 0.15996
  • 23. Effper 0.58199 0.26098 - 0.48570 0.02654 1.00000 - 0.05965 stdx1x4 - 0.20520 - 0.51074 0.54015 0.15996 - 0.05965 1.00000
  • 24. The SAS System 12:27 Wednesday, December 2, 1992 93 Obs Cases Runmin Downmin Setupmin Effper stdx1 stdx2 stdx3 1 33551 1027.17 222.3 177.12 80.6 0.56769 0.04684 - 0.25773 2 24120 733.15 301.7 247.60 69.9 - 0.70069 0.78023 0.34515 3 28800 885.47 257.1 292.37 75.6 - 0.04360 0.36828 0.72812 4 36504 1094.37 249.8 93.90 81.5 0.85758 0.30085 - 0.96960 5 34776 1061.37 89.8 288.82 90.6 0.71522 - 1.17702 0.69775 6 35064 1071.67 348.1 20.27 74.1 0.75966 1.20882 - 1.59943 7 31390 954.95 171.9 299.87 83.6 0.25615 - 0.41869 0.79227 8 28008 846.90 99.1 314.05 88.8 - 0.20998 - 1.09111 0.91357 9 33264 1159.02 101.0 180.00 79.2 1.13648 - 1.07357 - 0.23310 10 27028 1259.98 0.0 180.00 64.4 1.57205 - 2.00647 - 0.23310 11 22680 1019.83 240.0 180.00 54.0 0.53605 0.21033 - 0.23310 12 31392 975.52 142.4 319.97 84.3 0.34487 - 0.69117 0.96421 13 25992 782.85 270.6 373.48 74.0 - 0.48629 0.49297 1.42193 14 17314 468.18 289.1 177.55 68.6 - 1.84374 0.66385 - 0.25405 15 32327 963.37 205.6 242.85 83.0 0.29246 - 0.10741 0.30452 16 11592 352.37 138.7 27.22 70.8 - 2.34337 - 0.72534 - 1.53998 17 22104 660.32 134.0 0.00 83.5 - 1.01489 - 0.76875 - 1.77282 18 36576 1108.13 291.9 39.98 78.4 0.91697 0.68972 - 1.43083 19 24912 758.97 292.2 388.82 71.1 - 0.58932 0.69249 1.55315 20 33509 1004.95 223.7 211.35 81.8 0.47184 0.05977 0.03507 21 20016 618.53 492.8 297.03 54.0 - 1.19514 2.54536 0.76798 Obs stdx4 stdx1x2 stdx1x3 stdx1x4 stdx2x3 stdx2x4 stdx3x4 1 0.48457 0.02659 - 0.14631 0.27508 - 0.01207 0.02270 - 0.12489 2 - 0.59562 - 0.54670 - 0.24185 0.41734 0.26930 - 0.46472 - 0.20558 3 - 0.02019 - 0.01606 - 0.03175 0.00088 0.26815 - 0.00744 - 0.01470 4 0.57543 0.25801 - 0.83151 0.49348 - 0.29170 0.17312 - 0.55793 5 1.49409 - 0.84183 0.49905 1.06861 - 0.82126 - 1.75857 1.04250 6 - 0.17162 0.91829 - 1.21502 - 0.13037 - 1.93341 - 0.20745 0.27449 7 0.78742 - 0.10724 0.20294 0.20170 - 0.33171 - 0.32968 0.62385 8 1.31237 0.22911 - 0.19183 - 0.27557 - 0.99681 - 1.43195 1.19894 9 0.34324 - 1.22009 - 0.26491 0.39008 0.25024 - 0.36849 - 0.08001 10 - 1.15085 - 3.15426 - 0.36644 - 1.80919 0.46770 2.30915 0.26826 11 - 2.20075 0.11275 - 0.12495 - 1.17971 - 0.04903 - 0.46289 0.51299 12 0.85809 - 0.23836 0.33253 0.29593 - 0.66643 - 0.59308 0.82738 13 - 0.18171 - 0.23973 - 0.69146 0.08836 0.70098 - 0.08958 - 0.25838 14 - 0.72685 - 1.22397 0.46841 1.34013 - 0.16865 - 0.48252 0.18466 15 0.72685 - 0.03141 0.08906 0.21257 - 0.03271 - 0.07807 0.22134 16 - 0.50476 1.69975 3.60874 1.18284 1.1 1701 0.36612 0.77732 17 0.77733 0.78020 1.79921 - 0.78890 1.36286 - 0.59758 - 1.37806 18 0.26247 0.63245 - 1.31203 0.24068 - 0.98686 0.18103 - 0.37556 19 - 0.47447 - 0.40809 - 0.91530 0.27962 1.07554 - 0.32857 - 0.73693 20 0.60571 0.02820 0.01655 0.28580 0.00210 0.03621 0.02124 21 - 2.20075 - 3.04206 - 0.91784 2.63021 1.95478 - 5.60171 - 1.69013 Model search: Now we apply three search algorithms namely stepwise regression, backwards regression and best subset regression algorithm. The criteria for model selection used to evaluate the possible models are higher R2, R2a; lower MSE, PRESS, as well as lower number of predictor variables and Cp close to p. We have included the following variables in the model search algorithms:Run_Min, Down_min, Schedule_min, eff_per, and other interaction terms. The model has been standardized because the values of the predictor’s variables and response variable have varying magnitudes. a. Selection process: The different procedures for model selection were done and the results were obtained . The resultsa for the different procedures are as follows : 1: Best Sub Set model…..
  • 25. First best set The REG Procedure Model: MO EL1 D Dependent Variable: Cases Adjusted R-Square Select ion Method Number of Observations Read 21 Number of Observations Used 21 Number in Adjusted Model R-Square R-Square C(p) AIC SBC Variables in Model 3 0.9951 0.9958 13.7203 262.2361 266.41422 Runmin Downmin Effper Second Best set : 5 0.9969 0.9977 6.0000 254.1113 260.37839 Runmin Downmin Setupmin Effper The new Subset obtained are: Dependent Variable: Cases Adjusted R-Square Select ion Method Number of Observations Read 21 Number of Observations Used 21 Number in Adjusted Model R-Square R-Square C(p) AIC SBC Variables in Model 3 0.9951 0.9958 3.2091 262.2361 266.41422 Runmin Downmin Effper Similarly the other process of Backward deletion and Stepwise regression were carried out .The output is as follows : The SAS System 12:27 Wednesday, December 2, 1992 105 The REG Procedure Model: MO EL1 D Dependent Variable: Cases Number of Observations Read 21 Number of Observations Used 21 Stepwise Select ion: Step 1 Variable Runmin Entered: R-Square = 0.7271 and C(p) = 1732.637
  • 26. Analysis of Variance Sum of Mean Source DF Squares Square F Value Pr > F Model 1 663351807 663351807 50.63 <.0001 Error 19 248945175 13102378 Corrected Total 20 912296982 Parameter Standard Variable Est imate Error Type I I SS F Value Pr > F Intercept 5888.80747 3225.28395 43678620 3.33 0.0836 Runmin 24.84462 3.49169 663351807 50.63 <.0001 Bounds on condit ion number: 1, 1 ------------------------------------------------------------------------------------------------------ Stepwise Select ion: Step 2 Variable Effper Entered: R-Square = 0.8658 and C(p) = 845.6608 Analysis of Variance Sum of Mean Source DF Squares Square F Value Pr > F Model 2 789838790 394919395 58.05 <.0001 Error 18 122458192 6803233 Corrected Total 20 912296982
  • 27. The SAS System 12:27 Wednesday, December 2, 1992 106 The REG Procedure Model: MO EL1 D Dependent Variable: Cases Stepwise Select ion: Step 2 Parameter Standard Variable Est imate Error Type I I SS F Value Pr > F Intercept - 11419 4638.30362 41235217 6.06 0.0241 Runmin 21.91167 2.60637 480833856 70.68 <.0001 Effper 262.99050 60.99227 126486982 18.59 0.0004 Bounds on condit ion number: 1.0731, 4.2923 ------------------------------------------------------------------------------------------------------ Stepwise Select ion: Step 3 Variable Downmin Entered: R-Square = 0.9958 and C(p) = 13.7203 Analysis of Variance Sum of Mean Source DF Squares Square F Value Pr > F Model 3 908495108 302831703 1354.11 <.0001 Error 17 3801874 223640 Corrected Total 20 912296982 Parameter Standard Variable Est imate Error Type I I SS F Value Pr > F Intercept - 28901 1132.80996 145571123 650.92 <.0001 Runmin 24.46158 0.48535 568081327 2540.16 <.0001 Down min 26.43461 1.14763 118656318 530.57 <.0001 Effper 387.74395 12.31346 221757766 991.59 <.0001 Bounds on condit ion number: 1.3806, 11 .529 ------------------------------------------------------------------------------------------------------ Stepwise Select ion: Step 4 Variable stdx1x4 Entered: R-Square = 0.9975 and C(p) = 5.2554
  • 28. The SAS System 12:27 Wednesday, December 2, 1992 107 The REG Procedure Model: MO EL1 D Dependent Variable: Cases Stepwise Select ion: Step 4 Analysis of Variance Sum of Mean Source DF Squares Square F Value Pr > F Model 4 909984098 227496024 1573.77 <.0001 Error 16 2312884 144555 Corrected Total 20 912296982 Parameter Standard Variable Est imate Error Type I I SS F Value Pr > F Intercept - 28237 933.96796 132134456 914.08 <.0001 Runmin 25.15032 0.44533 461068290 3189.56 <.0001 Down min 24.42755 1.1 1462 69428305 480.29 <.0001 Effper 375.20126 10.64318 179646862 1242.76 <.0001 stdx1x4 425.29879 132.51505 1488990 10.30 0.0055 Bounds on condit ion number: 2.0148, 28.068 ------------------------------------------------------------------------------------------------------ Al l var iables le f t in the model are signi f i cant at the 0.1000 level . No other var iable met the 0.1000 signi f i cance level for entry in to the model. Summary of Stepwise Select ion Variable Variable Number Part ia l Model Step Entered Removed Vars In R-Square R-Square C(p) F Value Pr > F 1 Runmin 1 0.7271 0.7271 1732.64 50.63 <.0001 2 Effper 2 0.1386 0.8658 845.661 18.59 0.0004 3 Downmin 3 0.1301 0.9958 13.7203 530.57 <.0001 4 stdx1x4 4 0.0016 0.9975 5.2554 10.30 0.0055 To find out the outliers , we use the below terms : Run_min ,down_min,eff_per (std x1,x4) F*=MSR/MSE=302831703 F*=1354.103 Run_min:1000 Down_min: 250 Eff_per: 90 From Annova Table
  • 29. Run_min,Down_min,Eff_per X=2P/n=2*4/21=0.38095 Obsv10 =hii=.6296 16= hii= 0.4634 21= hii=.4359 Finv=3.297 No Youtliers Conclusion The conclusion of this analysis is The water line at America's Beverage Company (Kroger Manufacturing) is the main source of income for the manufacturing plant and the number of cases of water produced during the month of October was 591,092. Also, there are three (3) more soft drinks lines, which are not returning the pertinent dividends because of marketing purposes but increasing costs of production for the facility. At this point, it is imperative to maximize the number of water cases processed in the water line in order to keep the plant running and justify any capital appropriation requested to the General Office. In our final model the response variable has a linear correlation with the predictor variables. The final MLR model form is reasonable. The final model satisfied all the model assumptions and has constant variance, normality is OK, multicollinearity problem is eliminated.