EWMA-Jim

Annonymous,

I can buy into most of this but I think the criticality of point #3 needs to be stressed. It isn't a chart I would use in a moderately successful program.

You might even be able to launch a program that started with this easier than trying to upgrade a shakey system.

In terms of an automated SPC system, I really have never seen one that runs as well as the one that still does the calculations by hand. It lets people ignore the system to easily.

I had a factory in Chicago once that had an automated system. The chart proliferation was insane - 1200 charts when I got there. Over 4000 OOC points per week. It was impossible to react to anything (many of the charts were just set up incorrectly). If this was done without the system then it would have never happened.

I got a report (printout) of every point on every chart weekly - like I could do anything with that. What I did find was a lady who entered in under the comments section "Does anyone read this ___ report?"

With afew hours of training she was an SPC auditor and we started investigating poorly designed charts. Got it down to 900 before I left - still to many.

After that lengthy diatribe on automated SPC - I think it is dangerous. As you did say it enables a more sophisticated type of chart.

The other point is since it is sensitive to small changes the measurement system must be able to make the measurement in a shop floor environment and still pass an MSA.