Groups that can potentially be blinded in RCTs

Participants

Individuals who are randomly assigned to the interventions being evaluated


Healthcare providers

The physicians, nurses, physiotherapists, or other personnel who care for the participants during the study period or administer the interventions


Data collectors

Individuals who collect data for the study outcomes. Data collection could include administering a questionnaire, taking a physical measurement, or eliciting symptoms


Judicial assessors of outcomes

The individuals who ultimately decide whether a participant has had the outcome, or outcomes, of interest


Data analysts

The individuals who conduct the data analysis


Data safety and monitoring committee

The committee that reviews the data to advise on the continuing safety of the trial and persistent uncertainty of the efficacy of the intervention being evaluated


Manuscript writers

The individuals who write versions of the manuscript before the breaking of the randomisation code: in a fully blinded study, one version is written with the assumption that group A received the experimental intervention, and the other is written with the assumption that group B received the experimental intervention