I've been trying to replicate the results in this online calculator:
However, it seems that I am missing something. Exactly how do I solve the margin of error when all the other variables (sample size, confidence level, distribution and population*) are known?
I've tried to use the formulas on the page but I cannot arrive at the same result. Also using the formulas on bottom of http://www.resolutions.co.nz/sample_sizes.htm gives me somewhat different results. What am I missing?
*) = a small population so it cannot be assumed infinite.