The DPMO method to calculate the capability of a process is useful when there is more than one aspect of quality being measured. With two or more quality aspects, the Sigma method ( • Sigma Method for Proce... ) does not work.
Measure only quality characteristics that matter, don't go overboard, this is why they are called "critical to quality" or CTQs.
The table used in this video is derived from the standard Normal distribution N(0,1) and is free of the arbitrary 1.5 sigma adjustment featured in many books. The 1.5 sigma shift implies that the process is not stable, in which case the calculation of capability value makes no sense at all.
Assumption for using this method: the process is normally distributed with a known average and standard deviation.
8 сен 2024
