Re: Sample size and systematic sampling [message #3418 is a reply to message #3413] |
Sun, 07 December 2014 20:41   |
Reduced-For(u)m
Messages: 292 Registered: March 2013
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Senior Member |
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I can't answer your question (I don't do SPSS), but why do you only want a sample of 380? Is this for some sort of simulation or something? A sample size that comes from a power calculation is just the *minimum* sample size you would need to detect an effect of a certain pre-specified size. It doesn't mean you should throw out the remaining data. Am I missing something in what you are trying to do?
Also - in general you do need to account for the design effect, but where did 1.5 come from? You can specify a number of clusters (PSUs) and an inter-cluster correlation coefficient that will give you better power calculations based on beliefs or knowledge about the data, the extent of within-cluster correlation, and the number of clusters.
But maybe I'm just totally mis-understanding what you are trying to do. In that case, very sorry.
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