I describe the use of the Bonferroni and Holm formulas as approximations for Sidak and Holland–Copenhaver formulas when issues of precision are encountered, especially with q-values corresponding to very small p-values. Copyright 2013 by StataCorp LP.

Multiple-test procedures are increasingly important as technology in- creases scientists’ ability to make large numbers of multiple measurements, as they do in genome scans. Multiple-test procedures were originally defined to input a vector of input p-values and an uncorrected critical...