Discussion

Note, if there is no good evidence for differential expression in the experiment, that it is quite possible for all the adjusted $ p$-values to be large, even for all of them to be equal to one. It is quite possible for all the adjusted p-values to be equal to one if the smallest $ p$-value is no smaller than '1/ngenes' where 'ngenes' is the number of genes with non-missing $ p$-values. Note that $ p$-values adjusted to control the false discovery rate are often called $ q$-values [6].



Bjørn Kåre Alsberg 2006-04-06