sample size

[bartholomew]

Hi there

I know that for example when the general population is 1000, one has to select a sample size of 385 (cpnfidence level is 95%, E=0.05) What if the general population is 150? What is the optimum sample size assuming the same confidence level and margin of error?

[nucleardream]

How big of an effect size do you want for yourr reserach? Typically, an ES can be determined from looking at meta-analyses of past research and taking the difference in group averages divided by the shared standard deviation.

[WaldoMcFroog]

I'm guessing your 0.05 is a typo, because it would require you interview 150 people!!

If you meant 5 - that standard confidence interval used, then you would need to interview 108 people.

And no, I'm not a genuis at working sample levels out, I used this:

http://www.surveysystem.com/sscalc.htm :-)