Scaling Techniques
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The document provides an overview of educational research, focusing on measurement and scaling in the context of various scales such as nominal, ordinal, interval, and ratio scales. It explains the definition and components of attitude, classification of scales, measurement errors, reliability, and validity. The document emphasizes the importance of measuring constructs accurately through various scaling methods and tests to ensure reliability and validity in research findings.
Scaling Techniques
- 1. Basics of Educational RESEARCH Dr. C.V. Suresh Babu Scaling
- 2. Meaning of Measurement and Scaling Measurement: The term ‘measurement’ means assigning numbers or some other symbols to the characteristics of certain objects. When numbers are used, the researcher must have a rule for assigning a number to an observation in a way that provides an accurate description. Scaling: Scaling is an extension of measurement. Scaling involves creating a continuum on which measurements on objects are located.
- 3. Types of Measurement Scale Nominal scale: This is the lowest level of measurement. Here, numbers are assigned for the purpose of identification of the objects. Any object which is assigned a higher number is in no way superior to the one which is assigned a lower number. Example: • Are you married? (a) Yes (b) No Married person may be assigned a no. 1. Unmarried person may be assigned a no. 2. The assigned numbers cannot be added, subtracted, multiplied or divided. The only arithmetic operations that can be carried out are the count of each category. Therefore, a frequency distribution table can be prepared for the nominal scale variables and mode of the distribution can be worked out.
- 4. Types of Measurement Scale Ordinal scale: This is the next higher level of measurement. One of the limitations of the nominal scale measurements is that we cannot say whether the assigned number to an object is higher or lower than the one assigned to another option. The ordinal scale measurement takes care of this limitation. An ordinal scale measurement tells whether an object has more or less of characteristics than some other objects.
- 5. Types of Measurement Scale Example: Rank the following attributes while choosing a restaurant for dinner. The most important attribute may be ranked one, the next important may be assigned a rank of 2 and so on. In the ordinal scale, the assigned ranks cannot be added, multiplied, subtracted or divided. One can compute median, percentiles and quartiles of the distribution. The other major statistical analysis which can be carried out is the rank order correlation coefficient, sign test.
- 6. Types of Measurement Scale Interval scale: The interval scale measurement is the next higher level of measurement. It takes care of the limitation of the ordinal scale measurement where the difference between the score on the ordinal scale does not have any meaningful interpretation. In the interval scale the difference of the score on the scale has meaningful interpretation. It is assumed that the respondent is able to answer the questions on a continuum scale. The mathematical form of the data on the interval scale may be written as Y = a + b X where a ≠ 0 Ratio of the score on this scale does not have a meaningful interpretation.
- 7. Types of Measurement Scale Example: The numbers on this scale can be added, subtracted, multiplied or divided. One can compute arithmetic mean, standard deviation, correlation coefficient and conduct a t-test, Z-test, regression analysis and factor analysis.
- 8. Types of Measurement Scale Ratio scale: This is the highest level of measurement and takes care of the limitations of the interval scale measurement, where the ratio of the measurements on the scale does not have a meaningful interpretation. The mathematical form of the ratio scale data is given by Y = b X. In ratio scale, there is a natural zero (origin). Example: How many Pharmacy shops are there in your area? How many students are there in the M.Ed. Course at Sathyasai B.Ed. College? All mathematical and statistical operations can be carried out using the ratio scale data.
- 9. Definition of Attitude An attitude is viewed as an enduring disposition to respond consistently in a given manner to various aspects of the world, including persons, events and objects. Components of Attitude: Cognitive component (individual knowledge and information about an object) Affective component (person overall emotions and feelings) Intention or action component ( an aptitude reflects a pre disposition to an action by reflecting the consumer’s buying or purchase intention)
- 10. Classification of Scales Single item vs multiple item scale: • In the single item scale, there is only one item to measure a given construct. • In multiple item scale, there are many items that play a role in forming the underlying construct that the researcher is trying to measure. This is because each of the item forms some part of the construct which the researcher is trying to measure.
- 11. Classification of Scales Comparative vs non-comparative scales
- 12. Classification of Scales Comparative scales – In comparative scales it is assumed that respondents make use of a standard frame of reference before answering the question. Example:-
- 13. Classification of Scales Formats of Comparative Scales – Paired comparison scales Rank order scale Constant sum rating scale Q-sort technique Non-Comparative Scales – In the non-comparative scales, the respondents do not make use of any frame of reference before answering the questions.
- 14. Paired comparison scales • A respondent is presented with two objects and is asked to select one according to whatever criterion he/she wants to use. • Eg: Suppose a parent wants to offer one out of the two from among the four items to a child- chocolate, burger, ice cream and pizza. i,e chocolate or burger, chocolate or ice cream, chocolate or pizza, burger or ice cream ,burger or pizza and ice cream or pizza. • In general if there are n items, no. of paired comparison would be n(n-1)/2
- 15. RANK ORDER SCALING In this scaling the respondents are presented with several objects simultaneously and asked to order or rank them according to some criterion. Eg: Rank the following soft drink in order of your preference Soft drinks Rank Coke Pepsi Limca Sprite Mirinda
- 16. CONSTANT SUM RATING SCALE • In this scale the respondents are asked to allocate a total of 100 points between various aspects of the object. Characteristics of Toilet soap Points Fragrence 20 Color 20 Lather 20 Shape 20 Size 20 Total Points 100
- 17. Q- sort technique • In this Q-sort technique , a rank order procedure is used in which objects are sorted into different piles based on their similarity with respect to certain criterion • Suppose there are 100 statements and an individual is asked to pile them into five groups , in such a way ,that the strongly agreed statements could be put in one pile, agreed in another pile, neutral from the third pile, dis-agreed in the fourth pile and strongly dis-agreed statement form the fifth pile and so on.
- 18. Classification of Scales Graphic Rating Scale – This is a continuous scale and the respondent is asked to tick his preference on a graph. Examples: Non-comparative scale Graphic rating scale Itemized rating scale
- 19. Classification of Scales Please put a tick mark (•) on the following line to indicate your preference for fast food. Alternative Presentation of Graphic Rating Scale – Please indicate how much do you like fast food by pointing to the face that best shows your attitude and taste. If you do not prefer it at all, you would point to face one. In case you prefer it the most, you would point to face seven.
- 20. Classification of Scales Itemized rating scale – In the itemized rating scale, the respondents are provided with a scale that has a number of brief descriptions associated with each of the response categories. There are certain issues that should be kept in mind while designing the itemized rating scale. Number of categories to be used Odd or even number of categories Balanced versus unbalanced scales Nature and degree of verbal description Forced versus non-forced scales Physical form
- 21. Classification of Scales Examples of Itemized Rating Scales: Likert scale The respondents are given a certain number of items (statements) on which they are asked to express their degree of agreement/disagreement. This is also called a summated scale because the scores on individual items can be added together to produce a total score for the respondent. An assumption of the Likert scale is that each of the items (statements) measures some aspect of a single common factor, otherwise the scores on the items cannot legitimately be summed up. In a typical research study, there are generally 25 to 30 items on a Likert scale.
- 22. Classification of Scales Example of a Likert Scale:
- 23. Classification of Scales Semantic Differential Scale This scale is widely used to compare the images of competing brands, companies or services. Here the respondent is required to rate each attitude or object on a number of five-or seven-point rating scales. This scale is bounded at each end by bipolar adjectives or phrases. The difference between Likert and Semantic differential scale is that in Likert scale, a number of statements (items) are presented to the respondents to express their degree of agreement/disagreement. However, in the semantic differential scale, bipolar adjectives or phrases are used.
- 24. Classification of Scales Example of Semantic Differential Scale:
- 25. Classification of Scales Example of Semantic Differential Scale: (Pictorial Profile)
- 26. Classification of Scales • Stapel Scale Staple scale is used to measure the direction and intensity of an attitude.
- 27. Measurement Error This occurs when the observed measurement on a construct or concept deviates from its true values. Reasons Mood, fatigue and health of the respondent Variations in the environment in which measurements are taken A respondent may not understand the question being asked and the interviewer may have to rephrase the same. While rephrasing the question the interviewer’s bias may get into the responses. Some of the questions in the questionnaire may be ambiguous errors may be committed at the time of coding, entering of data from questionnaire to the spreadsheet
- 28. Criteria for good measurement Reliability Reliability is concerned with consistency, accuracy and predictability of the scale. Methods to measures Reliability Test–retest reliability Split-half reliability Cronbach’s Alpha
- 29. Test–retest reliability • In this repeated measurements of the same person or group using the same scale under the similar condition are taken.A very high correlation between the two scores indicates that the scale is reliable.Following issues should be kept in mind before arriving at such conclusion • The time difference between the two observations is a question which is requires attention • The first measurement may change the response of the subject to the second measurement • Situational factors working on two different time periods mat not be the same which may result in different measurement in the two periods
- 30. Split-half reliability • This method is used in the case of multiple item scales.Here the no.of items is randomly divided into two parts and correlation coefficient between the two is obtained. • A high correlation indicates that the internal consistency of a multiple item scale is the co-efficient alpha commonly known as cronbach alpha.It computes the average of all possible split half reliabilities for a multiple item scale. • The alpha coefficient can takes values between 0 and 1
- 31. Cronbach alpha ( Interpretation of alpha Alpha=0 There is no consistency between the various items of a multiple item scale Alpha=1 There is complete consistency between the various items of a multiple item scale 0.8≤alpha ≤0.95 There is a very good reliability between the various items of a multiple item scale 0.7≤alpha ≤0.8 There is a good reliability between the various items of a multiple item scale 0.6≤alpha ≤0.7 There is a fair reliability between the various items of a multiple item scale Aplha<0.6 There is a poor reliability between the various items of a multiple item scale
- 32. Criteria for good measurement Validity The validity of a scale refers to the question whether we are measuring what we want to measure. Different ways to measure Validity Content validity Concurrent validity Predictive validity
- 33. Content validity • It also called as face validity in which an expert provides subjective judgement to assess the appropriateness of the construct. Eg: To measure the perception of a customer towards Uber and OLA Concurrent validity It is used to measure the validity of the new measuring technique by correlating them with the established technique. It involves computing the correlation coefficient of two measures of the same phenomena.
- 34. Predictive validity • The ability of a measured phenomena at one point of time to predict another phenomena. If the correlation between the two is high, the initial measure is said to have a high predictive ability. Example: Use of TET to shortlist candidates for the interview in a school. Sensitivity Sensitivity refers to an instrument’s ability to accurately measure the variability in a concept.