Observed fraction of false positives and false negatives among 633 negative controls on each microarray chip and among 40 distinct genes as positive controls using reported qa cluster genes.

The estimated power is 1 – fraction of false negatives observed. The fraction of false positives observed can be compared with the nominal significance level used to identify genes that are: (1) QA-responsive in WT; (2) starvation-responsive in WT; (3) QA-responsive in qa-1F. The gene expression level-50 (GEL50) is a proxy for power [50] and allows comparison of power properties of the experiments below with other published experiments.