Sample Size Calculators
DCR-4 Chapter 6 “Estimating Sample Size and Power” Appendixes A-F provide instructions and tables for calculating sample sizes. However, the tables provided for two-group studies assume that the groups are of equal size. If you have unequal group sizes (as occurs in most observational studies) or a study parameter that does not correspond to one of the table headings, then you may have to use one of these online calculators.
Online Calculators Corresponding to Tables in DCR-4 Chapter 6
Two-group analytic study comparing
(A) group means
(A-1) sample size given effect size
(A-2) effect size given sample size
(B) group proportions
(B-1) sample size given both proportions
(B-2) second proportion given sample sizes and first proportion
One-group analytic study comparing
(C) the correlation coefficient to zero (or another specified value)
One-group descriptive study estimating
(D) a mean
(E) a proportion
One-group analytic study comparing
(F) the mean change score to zero
Online Calculators Corresponding to Other Sample Size Problems