Proportion Difference Sample Size Calculations
This calculator determines the sample size required to detect a difference
between two proportions. The calculator is for planning purposes only. For
assistance with this calculator or any other sample size calculations including
non-proportion sample size (e.g. a difference in means) please contract us for a
free consultation.
Example: This calculator will determine the number of patients required to
detect a difference between two proportion. An example would be the % of
patients require a repeat surgery in the first year after an intervention. Other
examples include % mortality, % experiencing an adverse event, % with a certain
level of pain relief.
This calculator incorporates a continuity correction to the usual sample-size
formula which increases the sample size (for each group) by an amount
approximately equal to 2/abs(p1-p2), where p1 and p2 are the population
proportions for the two groups.