Table 1. Sample Size for Frequency in a Population (from OpenEpi, Version 3, open source calculator—SSPropor).

Sample Size for Frequency in a Population
Population size(for finite population correction factor or fpc)(N):	1300
Hypothesized % frequency of outcome factor in the population (p):	50%+/-5
Confidence limits as % of 100(absolute +/- %)(d):	5%
Design effect (for cluster surveys-DEFF):	1
Sample Size(n) for Various Confidence Levels
Confidence Level (%)	Sample Size
90%	225
95%	297
99%	440
Equation
Sample size n = [DEFF*Np(1-p)]/ [(d2/Z21-α/2*(N-1)+p*(1-p)]