Statistical Power calculations

Statistical power calculations are often needed at various stages of planning for establishing sample sizes.
Elsewhere on this Blog I mention PiFace as a power calculation tool. However SAS users may find the following three SAS macros of interest.
UnifyPow is an extensive collection of power calculators implemented in SAS as a Macro. A SAS proceedings paper about UnifyPow discusses its broad generality. The second macro is rpower and addresses the reprospective aspect of the issue. The third macro, glimmixsamplesize, is designed to use the generality of SAS’s Proc Glimmix for generalized linear mixed models. These macros provide a substantial increase in the number of settings that can be addressed for power calculations.