Re: C Chart Issues - Posted Data and Charts in Post #7
Fundamental problem is that you are not plotting counts - you are plotting defects per units. These are not c charts, so the c chart control limts (based upon the square root of the average) do not work. For defects per unit, you would need to go with u chart control limits. That is, the average plus 3 times the square root of (the average divided by the number of units per datum point).
"A Passionate Statistician", ASQ CQE, ASQ Fellow