StatTools : Sample Size for Estimating Population Proportion
Explained, Program and Tables

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Related link :
Sample Size Introduction and Explanation Page
Sample Size for Population Parameters Explanation Page

Introduction Tables for Sample Size Program References
Explanation Models & Nomenclature
This page provides tables and a Javascript program for samples size needed to establish the population proportion of a parameter.

Calculation of sample size and error for population proportions requires the use of the Binomial Coefficient to produce an approximate number, then use iterative calculations to obtain results that are increasingly precise, until the correct answer is given. As the Binomial Coefficient requires the calculation of Factorial numbers, the time require for computation increases exponentially with the sample size involved. The php engine usually allows a maximum of 30 seconds for any single process, and this is insufficient when the sample size exceeds 300.

This page provides tables for estimating sample size and error estimations that should suffice most research situations, and users are encouraged to use these.

On the exceptional occasion that the tables are insufficient, the Javascript program can be used. . The other is a Javascript program to perform those calculations required by the researcher, but not covered by the tables.

In most cases the sample size can be immediately obtained from the tables included in this page. If the user needs to calculate a sample size or confidence interval that cannot be obtained from the tables, a small Javascript program is provided for its calculation.

Please note however that some browsers have time limits, and when that limit is reached it asks the user whether to continue or not. Although long programs can be run, it does require the user to attend and repeatedly tell the browser to continue. The limits are as follows.

  • Internet Explorer - 5 million statements
  • Firefox - 10 secs
  • Safari - 5 secs
  • Chrome - no time limit
  • Opera - no time limit