What is an advantage of cohort studies regarding temporality?

• A. Temporality unclear
• B. They establish temporality
• C. They cannot measure exposure
• D. They require randomization

Answer: (B)

In a cohort study you start by determining each participant’s exposure status and then follow them over time to see who develops the outcome. Because you observe exposure before the outcome occurs, you can establish that exposure preceded the outcome, giving a clear time order. This is especially true in prospective cohorts, where exposure data are collected before any outcome happens, reducing biases and clarifying the sequence of events. That time-ordered information is what makes cohort designs particularly strong for assessing temporality.

Cohort studies do measure exposure, and they are observational rather than randomized, so those points also don’t fit as advantages. The key benefit here is the ability to establish that the exposure comes before the outcome.