Summary
ABSTRACT Randomized controlled trials (RCTs) are the gold standard for assessing interventions for preventing and treating cancer, but their external validity is only guaranteed if the trial participants are a random sample from the target population. Unfortunately, most cancer-related RCTs use convenience samples, not probability samples, and differences between the trial sample and the target population are likely to exist. If these differences are related to the effectiveness of the treatment being studied (“effect modifiers”), trial results will fail to generalize. While observable differe
