q-value (statistics)

In statistical hypothesis testing, specifically multiple hypothesis testing, the q-value in the Storey-Tibshirani procedure provides a means to control the positive false discovery rate (pFDR). Just as the p-value gives the expected false positive rate obtained by rejecting the null hypothesis for any result with an equal or smaller p-value, the q-value gives the expected pFDR obtained by rejecting the null hypothesis for any result with an equal or smaller q-value.