This Webulator is based on the following sample size formula for a case-control study.

The [Zalpha ] and [Zbeta] terms use the “common statistical terms” which are 1.96 to represent the Zalpha term and 0.84 to represent the one tailed Zbeta term. Simply substitute these values into the equation, or into the webulator to compute the number of subjects required in each group for a case-control study.

Only enter the numeric values into the green boxes and click the button labelled "calculate" to compute the sample size. Do not enter any special characters into the Webulator. The sample size refers to the sample size required to represent the number of subjects for each group in a case control study.

p1 = the proportion of
exposure among
cases		 p0 = the proportion of
exposure among
controls		 Z1-alpha/2 Z1-beta
Sample Size Score is: The Numerator value is: The Denominator value is: