Observed fraction of false positives and false negatives among 633 negative controls on each microarray chip (see Materials and Methods) and among 43 distinct genes as positive controls using reported clock-associated genes [93].

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) circadian; (2) light-responsive; (3) WCC-responsive.*The nominal significance level was adjusted using the positive and negative controls to insure that the estimated power was high.