Mr. Sambuddha,
I am a statistician by profession and as far as I know, sample size is determined by margin of error allowed, the estimate for the population variance, the risk factors (level of confidence, power as a function of the OCC, etc.), and most importantly, the assumed distribution of the population (or the estimable function) in study.
In my own experience, the magic number 30 is being used to approximate the normal distribution using the Central Limit Theorem, as used in regression analysis, factor analysis, etc., but not in sample size determination.
I am also curios with this article. Would you be kind enough to send me a copy, too? Also, would you happen to know/ recommend six sigma training centers in the Philippines?
Thanks,
Beryl
[email protected]
