Past exam of the mathematics course of the University of Cambridge / 2012 / iii / Paper 41 / 1 / a / i

Screening applies the eligibility criteria for a clinical trial before treatment allocation. It identifies the population to which the comparison pertains and excludes individuals for whom the intervention or measurements are unsuitable. Recording potentially eligible individuals also helps describe recruitment and assess external validity. It should precede randomization so eligibility is not decided using knowledge of the allocated treatment.