Unit4 Proof of Correctness, Statistical Tools, Clean Room Process and Quality Circles
- 1. 1 Proof of Correctness, Statistical Tools, Clean Room Process and Quality Circles Cotterell Vth Edition
- 2. Testing and Proof of Correctness • Program Testing – Seeks to show that particular input values produce acceptable output values. – Testing can prove the presence of errors but never their absence – It is a major part of software development (some tools could help, e.g.. Junit in Eclipse, a java IDE)
- 3. Testing and Proof of Correctness (cont.) • Proof of correctness – Use the technique of a formal logic system to prove that if the input values satisfy certain constraints, the output values produced by the program, satisfy certain properties. • The difference between proof of correctness and testing. For example, a program to compute the average of two number x1,x2. – Testing takes each possible input of x1, x2, the result is (x1+x2)/2 – Proof of correctness establishes that the result is the average (Mathematical Models)
- 4. 4 Statistical Tools Cotterell Vth Edition
- 5. Total Quality Control Total Quality Control (TQC) – A Systems Approach ‘A management framework to ensure continuing excellence’ This framework may include following statements/ programmes for actions: • TQC is a business philosophy which groups together manufacturing, engineering, marketing, and sales amongst others, linked together by a two way flow of information; • TQC should be considered as a mind-set to approve only criteria which lead to better than acceptable quality (via the use of continuous improvement); • TQC is a continuous process for improvement where current standards present the opportunity for the achievement of new and higher targets (standards); • TQC provides reliability and consistency in the delivered product/ service as a check-and-balance system. Mohamed Zairi
- 6. Srihari Techsoft Plan Do Check Action Software Development Process Cycle – Deming’s PDCA Cycle
- 7. Tools and Techniques for TQM/ Process Management Ishikawa’s tools for quality improvement • Elemental statistical techniques (seven) – Flow Charts – Graph and Shewart control chart/ Run charts or trend charts (Shridhar added Run charts with Control Charts) – Check sheets – Cause and effect diagrams (Fish-bone diagram) – Stratification/ Histograms – Pareto analysis – Scatter diagram (Correlation diagram) – Contd/-
- 8. Run Chart/ Trend Chart A run chart is a line graph in which data are plotted over time
- 9. Control Chart A simple run chart to which two horizontal lines are added – UCL and LCL • Control limits are chosen statistically so that there is a high probability (generally greater than 0.99) that points will fall between these limits if the process is in control. If Points fall outside these lines or are not random, process is not stable. • Control charts only give the signal when the process tends to go out of control and can not determine the source of the problem for which other problem solving techniques are to be used. K Shridhara Bhat – P 285
- 10. Check Sheets
- 11. Histograms • Histogram Defined – A histogram is a bar graph that shows frequency data. – Histograms provide the easiest way to evaluate the distribution of data.
- 12. Pareto Charts • Pareto Chart Defined – Pareto charts are used to identify and prioritize problems to be solved. – They are actually histograms aided by the 80/20 rule adapted by Joseph Juran. • Remember the 80/20 rule states that approximately 80% of the problems are created by approximately 20% of the causes.
- 14. Fishbone Diagram (cause and effect) Largest Influence 2nd Largest Influence Least Influence 3rd Largest Cause Factors and/or categories of factors Effect Cause Cause Cause Cause Cause Cause Cause Cause Cause
- 15. Scatter Diagrams Slide 1 of 4 • Scatter Diagrams Defined – Scatter Diagrams are used to study and identify the possible relationship between the changes observed in two different sets of variables.