I have recently come across a website (http://www.surveysystem.com/sscalc.htm) that returns the sample size given the following inputs: confidence level, confidence interval, and population. I assume this is done by rearranging a hypothesis test under a CDF, I guess using the standard normal distribution? But, if one does not believe the data reflects this particular CDF, how would you go about using bootstrapping to arrive at a version of the sample size that is data driven and not limited to the ~N(0,1) distribution?
Further, I am interested in this procedure for stratifications of a sample.
Help on either, especially the first paragraph, would be appreciated.