Extending the Utility of Federal Data Bases. Effective Sample Sizes Required to Meet Precision Levels

05/01/2000

The effective sample sizes needed to provide the precision levels for the various prevalence rates are shown in Table 3-1. They were derived from the simple formula for simple random sampling,

n = 1 - p  ;
p(CV)2

where p is the prevalence rate.

Table 3-1.
Effective sample size needed for alternative prevalence rates and levels of precision
 Prevalence rate Precision level (CV)
.30 .20 .10
0.01 1,100 2,475 9,900
0.05 211 475 1,900
0.10 100 225 900
0.15 63 142 567
0.20 44 100 400