If you’re one of those that needs hard data, you can use Raosoft’ssample size calculator. Once you set themargin of errorandconfidence level, you’ll enter the population size and the response distribution to collect a hard figure you can use to gather the best data. Source Consider Dev...
The calculation of sample size was based on the Raosoft sample size calculator using a 5% margin of error and at a 95% confidence interval [http://www.raosoft.com/samplesize.html]. For this study it was recommended to use a minimum sample size of 385 participants based on the total ...