Change-point analysis is a powerful new tool for determining whether a change has taken place. It is capable of detecting subtle changes missed by control charts. Further, it better characterizes the changes detected by providing confidence levels and confidence intervals. When collecting online data, a change-point analysis is not a replacement for control charting. But, because a change-point analysis can provide further information, the two methods can be used in a complementary fashion. When analyzing historical data, especially when dealing with large data sets, change-point analysis is preferable to control charting. A change-point analysis is more powerful, better characterizes the changes, controls the overall error rate, is robust to outliers, is more flexible and is simpler to use. CPA aims at detecting any change in the mean of a process in historical data. Example questions to be answered by performing CPA:
• Did a change occur?
• Did more than one change occur?
• When did the changes occur?
• How confident are we that they are real changes?
http://…/changepoint.html … Change Point Analysis (CPA)