Rony.bond posted a topic in Discussions related to Green Belt, Black Belt, Lean ExpertThe significance of sample size come from manufacturing. This meant that to check for the accuracy of output per machine you need to audit x sample. i.e If Machine A produces 60,000 units you may want to audit 360 approx. sample. But this sample size is good for 60,000 units if produced by A. However, if 60,000 are produced collectively by A & B then what should be the sample size. The fact is if Machine A is 3 yrs old and Machine B is 6 yrs old. Should you 1. Audit 360 overall 2. Base sample size basis individual production 3. Divide 360 proportionately basis production The intent is to understand the impact of variable on sample size. Also, do you recommend stratified sample rather than random sample.