Analyzes the observed difference between a process median and a known value. This test is similar to the 1-sample t-test, and is used as an alternative for cases where the data are not reasonably normal.
|When to Use||Purpose|
|Pre-project||Verify the process is producing output significantly different from expectations, validating the need for an improvement project.|
|Mid-project||Test whether the output changes significantly when an input is controlled at a new setting or a previously uncontrolled setting is now controlled.|
|Mid-project||Verify changes from the pre-project standard throughout the course of making improvements.|
|End of project||Verify the median output from the controlled improved process is different from the pre-project median. Of course, this step assumes that one of the goals of the project was to shift the process median.|
Continuous Y (output).