require 4261 participants, half cases and half controls. Holding all else constant, hypothesizing a dominant mode of inheritance would require 5037 participants, whereas reducing the frequency of the risk allele by half (i.e., 0.005) would require 8021 participants. Similarly, to be able to detect an effect that is somewhat smaller in magnitude (e.g., OR = 1.1), though still very much in line with those frequently reported in the literature, would require 9296 participants. In contrast, to detect an effect of that same SNP (MAF = 0.1) accounting for 1% of the variability in a continuously distributed indicator of depression within a community sample would only require 781 individuals total. Thus, when estimating power for relatively straightforward designs, we suggest that social scientists utilize some of the free power calculation software that is available on-line (e.g., Quanto3).
