Standard and non-standard gene interactions. Displayed are density estimates of gene interactions as measured by the 27 standard tests (solid curve), for example w·ar - a·r, and by the 216 non-standard tests (dashed curve), for example ar·bs - as·br. The raw data are shown below the density curves.
Beerenwinkel et al. BMC Evolutionary Biology 2007 7:60 doi:10.1186/1471-2148-7-60