One issue with the use of t-statistic and associated p-values is that they are affected by both sample size and effect size.[18] They come from testing for no mean difference, and thus are not designed to measure the size of compound effects. For hit selection, the major interest is the size of effect in a tested compound. SSMD directly assesses the size of effects.[19] SSMD has also been shown to be better than other commonly used effect sizes.[20] The population value of SSMD is comparable across experiments and, thus, we can use the same cutoff for the population value of SSMD to measure the size of compound effects .[21]