Researchers plan to survey cannabis use frequency among high school students and will invite only students who have already used cannabis to participate. Should the REB require changing the protocol to include students who have never used cannabis?

• A. Yes
• B. No
• C. It depends
• D. Not sure

Answer: (B)

When evaluating a study with minors on a sensitive behavior, the key consideration is whether the recruiting plan matches the research question and minimizes risk. If the goal is to describe cannabis use frequency among students who have already used cannabis, recruiting only those students directly targets the population of interest. Including students who have never used cannabis would shift the population being described and not help answer the intended question; it would also complicate the study design, possibly requiring broader screening, more extensive confidentiality protections, and adjustments to consent processes. The REB would ensure appropriate safeguards for handling sensitive information and that consent/assent (and parental permission, as required) are properly obtained, but there is no ethical or methodological need to broaden the sample just to include never-users. Therefore, no protocol change is needed.