Problem Resolution Report Monitoring - Customer complaint or PRR as general motors use

[Graciel]

You mean SPC to monitor complaint number?

 

[John Predmore]

We´ll use monthly monitoring.

I know nothing about your business, so this is only an illustration based on my experience. The reason I suggested 6 month cumulative reporting is you will have good months (0 PRRs) and bad months (2,3 or more). You don't want to beat yourself up when you have a bad month, you don't want to pat yourself on the back when you have a single good month. The difference could be a factor beyond your control, like how long a PRR form sits in some buyer's in-basket. If a PRR you don't deserve is reversed, that reversal could take several months. If you feel the need to report monthly, it should be a moving average (or a 6-month running total) to smooth out the peaks and dips.

 

[Bev D]

We have a set of problems that are relatively rare, they occurrence is 0 to 4 per reporting period*. This range is actually statistically stable when we use the u prime chart. (aka the Laney chart. see: Laney, David B., “Improved Control Charts for Attributes”, Quality Engineering, 14(4), 2002, pp. 531-537). so as John says we don't randomly celebrate a zero occurrence or beat people up when 4 events occur.

*our reporting period is not time based it is lot based as our lots are consumed by the user over a 9-12 month period.