Proposed selection diagram representing the assumed causal model within the Iniciativa Profilaxis Pre-Exposición (iPrEx) study (multiple countries, 2007–2010) and assumed differences between the study population and each target population (Latino MSM Community Involvement Study: San Francisco and Chicago, 2004). Age is age at baseline; gender identity refers to transgender women who have sex with men or cisgender men who have sex with men; educational level is highest level attained; sexual role is primary sexual position (“top,” “bottom,” “versatile”); alcohol is prior month alcohol consumption; cocaine is prior month cocaine use; ncRAI is any condomless receptive anal intercourse in the 3 months prior to baseline; number of partners is total number of male partners in the 3 months prior to baseline. S, selection node; Z, treatment assignment.