The classic model is, you get a bunch of studies where you know that they've been conducted and completed, and then you go and see if they've been published anywhere in the academic literature. So this took all of the trials that had ever been conducted on antidepressants that were approved over a 15-year period by the FDA.
O modelo clássico é:  agarramos num punhado de estudos que sabemos que foram  realizados e completados e vamos ver se já foram publicados  na literatura académica. Selecionamos todas as experiências  que foram realizadas com antidepressivos e que foram aprovados pelo FDA,  num período de 15 anos.