Required sample size and sample error of a survey Calculator

Description
Before launching a survey it is important to establish the sample size. Due to budget and time limitations, you need to survey the minimum number of people that guarantee a certain data quality. This is the sample error you are willing to accept, and, based on this, you can calculate the minimum number of people you need to survey.

This Excel template has to sheets, where you can calculate the following:

- minimum sample size: before launching a survey you can establish the required sample size both for proportion questions (% of men vs women) and for means (age). You need to establish your confidence level (by default 95%), the error your are willing to accept, and the population size if you know it.

- sample error: once you get results, with this tool you can calculate the error of each question, both for proportion questions (% of men vs women) and for means (age). For example, if, according to the survey, 40% are men, and the calculate error is 3%, than the population average is probably between 37% and 43%. Or, if your mean age is 50, and the calculated error is 4, then the probable population age is between 46 and 54.