Which of the following is a key question when critiquing how subjects were chosen in a study?

When critiquing how subjects were chosen in a study, focusing on whether the subjects were chosen randomly is crucial because random selection helps ensure that the sample is representative of the larger population. This reduces selection bias and increases the generalizability of the study's findings. Random selection is fundamental to the integrity of experimental design, as it minimizes the impact of confounding variables and allows for a more accurate comparison between intervention and control groups.

Assessing whether subjects were selected based on past performance or from a wide range of sources can provide insights into potential biases introduced in the sample selection process, but these aspects do not directly address the randomness of selection. Similarly, questions about the maintenance of subjects for long-term observation relate more to study design and follow-up rather than the initial selection process. Thus, the focus on random selection is foundational to evaluating the validity of the study’s methodological approach.