Figure 2.

Statistical power in the Poisson multilevel model test for the association between the status of major depressive episode (MDE) and the number of previous attempts at the time of a new attempt. As the effect of MDE status on suicide attempts increases (x-axis), chances to detect it increase too (statistical power; y-axis). The less the between-patient differences explain differences in suicidality, the more rapid the increase in our ability to detect an effect of MDE status. That is, power is a function of both attempt multiplier per depression-status difference (effect size) and between-individual differences in the overall numbers of suicide attempts (random effect standard deviance; greater the value greater the differences). Statuses of a major depressive episode can be “remission” (reference category), “partial remission,” or “full MDE.” Horizontal dashed line highlights the point of 80% chance to detect an existing omnibus effect in data like ours.