Which study design is typically less time consuming and less expensive?

• A. Case-control study
• B. Cohort study
• C. Randomized controlled trial
• D. Cross-sectional study

Answer: (A)

Case-control studies are typically more time-efficient and cheaper because you start with people who already have the outcome of interest and a comparison group without the outcome, then look back to determine past exposures. This retrospective approach means you don't have to follow a large cohort forward for years to see who develops the condition, which cuts both time and costs. You can often use existing records or interviews to gather exposure data, and you usually need a smaller sample since the outcome drive the study design. In contrast, following people over time in a cohort study or conducting a randomized trial requires prolonged follow-up, more resources, and stricter monitoring, which drives up both duration and expense. Cross-sectional studies can be quick and inexpensive, but they capture data at one point in time and aren’t ideal for investigating rare outcomes or establishing temporality, making case-control designs the more resource-efficient choice when speed and cost are primary considerations.