Rather than setting a fixed pFDR rate to control, Storey and colleagues suggest giving a value to each test that indicates what pFDR would result from declaring that test significant. The follow-up tests can then be chosen based on joint consideration of the number of tests selected and the pFDR associated with them. Formally, the q-value associated with an individual test is defined as the minimum pFDR achieved when declaring all tests significant at the level of the test's p-value. A q-value can be estimated for each test in a genomewide experiment and follow-up tests selected from those with the lowest q-values. This last stage is somewhat informal and may be driven by logistic and financial constraints.
