Analyzes the difference between an observed process mean and a specified value.
|When to Use||Purpose|
|Pre-project||Verify the process is producing output significantly different from expectations, which validates 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 mean output from the controlled improved process is different from the pre-project mean. Of course, this step assumes that one of the goals of the project was to shift the process mean.|
Continuous Y (output)