Approximate sample size calculations with microarray data: an illustration.

We outline a method of sample size calculation in microarray experiments on the basis of pilot data and illustrate its practical application with both simulated and real data. The method was shown to be consistent (as the number of 'probed genes' tends to infinity) under general conditions in an earlier, more 'theoretical' companion paper. Its implementation requires the values of test statistics, the sample size with which the statistics are computed, and the knowledge of their distribution under the null hypothesis.