Hi, I got a problem in estimating sample size. I am preparing a survey (some sort of public opinion survey) among a group of 400 subscribers to a service. I want to draw a sample but don't know how many ill be statistically "sound". I got a formula n= z^2 (p x q) / e^2 where z=standard error associated with level of confidence p=estimated variability in the population q=100-p e=acceptable error Most of the questions in the questionnaire I use will be in likert scale. I have no idea of the variability of the population. There is no know means nor any parameters for comparison. I tried quite a lot of online sample size calculator and was required to provide information that I don't have e.g., variances, P1, P2 etc. Is there any better method? Thanks. =========================================================================== This list is open to everyone. Occasionally, less thoughtful people send inappropriate messages. Please DO NOT COMPLAIN TO THE POSTMASTER about these messages because the postmaster has no way of controlling them, and excessive complaints will result in termination of the list. For information about this list, including information about the problem of inappropriate messages and information about how to unsubscribe, please see the web page at http://jse.stat.ncsu.edu/ ===========================================================================
