Email this LII item:

Sample Size Calculator
Want to take a survey but not sure how many responses to collect? This calculator gives you the number for any given population size and desired confidence level. A reverse calculator lets you enter characteristics of an existing survey and gives the confidence interval (plus-or-minus number) to apply to the results. This site, sponsored by a survey software company, also gives clear explanations of statistical significance, survey design, and related concepts.
http://www.surveysystem.com/sscalc.htm

Asterisk * indicates required field.

*
*
*
(separate multiple addresses with commas)


*