boonlert wrote: > > Dear All > Can I use a non-parametric test for a sample size less than 30 (central > limit theorem) Sorry, but (i) what has the central limit theorem have to do with any of this? (ii) for that matter, what does a sample size of 30 really have to do with the central limit theorem in any case? The rate at which the CLT can be regarded as having kicked in sufficiently depends on what the sampling distribution is (sometimes n=1 is enough, sometimes n=10000 isn't enough), and what purpose you're wanting to use the theorem for. > regardless the scale, nominal or ordinal scale, requirement? Not sure what this sentence is asking. > If I can, what is the priority concern for using non-parametric test whether > sample size or measurement scales? I'm not sure what you are asking about. Could you please write in shorter sentences, because you seem to be assuming stuff that isn't necessarily true. About all I can glean from what you've written is that you have some concern about sample size and measurement scale for some (unspecified) nonparametric procedure or procedures. However it isn't at all clear which ones you care about, nor what the concern actually is. I will say that for almost all nonparametric procedures in common use, the tables usually go down to very small numbers - there is generally no minimum sample size (except as required to actually calculate the quantities involved). Note also that some nonparametric procedures may only be suitable for some measurement scales, but this has nothing to do with the sample size AFAIK. Glen