Figure 2.

Direct and comparative phenotype statements, and conversions between them. The upper part of the figure shows how phenotype statements are made in case/control experiments, in which the comparative phenotype statement expressed the difference of an observation to an explicitly or implicitly specified control. In the bottom figure, direct observations are made to two organisms, Organism 1 and Organism 2, and the comparative phenotype statements are derived by designating one of the two organisms as control and computing the differences between the other organism and the control.