Dan Watson
Involved In Discussions
I feel rather stupid for asking this question, but it is a reality check for me. I work with a QA Manager who has stated that the normality of the data does not matter when calculating capability indices for different product parameters. His numbers are pretty much always above 1.33. I thought, since I have been taught since 1987, that if the data are non-normally distributed, that the descriptive statistics for normally distributed data cannot be used. The root cause of why the data are non-normally distributed needs to be investigated, i.e., what are the causes of the special variation influencing the data. Am I wrong? Would process capability indices be an alternative measure until the data distribution is more normal? This individual will rework PPAP numbers that the technicians give to him to that the numbers "look appropriate." Sometimes the old saying is true, 'torture the numbers enough and they'll confess to anything."