Fig. 3From: Assessing risk of bias: a proposal for a unified framework for observational studies and randomized trialsI stands for treatment status, Oi for intermediate outcome status, Oe for outcome status at endpoint, and S for a common effect (selection). The arrow with question mark stands for the causal question (effect) of interest. The box around S signifies that exclusion of patients based on treatment and outcome occurred as a result of the design or the analysisBack to article page