cpk under 2 conditions, first the process must be stable, in control, second, the data collect must be normal distribution, cpk has specific meaning, it is useful, it tells you sth about your process. cpk should not be less than 1, otherwise, the process is not good.
ppk is calculated from data collected in a long term. the process is not stable, or say out of control. so in my point of view, ppk is not meaningful. because the process is not stable, you do not know what the ppk tell you exactly.
RSS Feed
7 个回复
Nicktang (威望:0)
赞同来自:
ppk is calculated from data collected in a long term. the process is not stable, or say out of control. so in my point of view, ppk is not meaningful. because the process is not stable, you do not know what the ppk tell you exactly.