1 In some quantitative research stricter confidence levels are used eg. Necessary Sample Size Z-score2 StdDev 1-StdDev margin of error2 This equation is for an unknown population size or a very large population size. The confidence interval also called margin of error is the plus-or-minus figure usually reported in newspaper or television opinion poll results.
If the population is N then the corrected sample size should be 186N N185.
This sample size calculator determines the number of participants given a particular confidence interval. Sample Size z2 p 1-p e2 1 z2 p 1-p e2 N N population size. The confidence interval also called margin of error is the plus-or-minus figure usually reported in newspaper or television opinion poll results. If you have a small to moderate population and know all of the key values you should use the standard formula.