Study Design Classification
This is a cohort study (Option A). When researchers divide participants into groups based on an exposure (watching TV for 2 hours daily vs. not watching TV) and then follow them over time to observe health outcomes, this defines a prospective cohort study design 1, 2.
Key Distinguishing Features
Why This is a Cohort Study
- Exposure-based grouping at baseline: Participants are selected and categorized based on their TV-watching behavior (exposed vs. unexposed) before any outcomes occur 1, 2
- Temporal sequence: The exposure (TV watching) precedes the outcome measurement, establishing clear temporality between exposure and any subsequent health effects 1, 3
- Longitudinal follow-up: The design implies following both groups forward in time to compare outcome incidence rates between exposed and unexposed groups 2, 3
Why Other Options Don't Fit
- Not case-control (Option B): Case-control studies start by identifying people with the outcome (cases) and without the outcome (controls), then look backward to assess past exposures. This question describes the opposite approach 1
- Not cross-sectional (Option C): Cross-sectional studies measure exposure and outcome simultaneously at a single point in time, providing a "snapshot" rather than following participants over time 4
- Not randomized controlled trial (Option D): RCTs involve random assignment of interventions by investigators. The question describes observational grouping based on existing behavior, not experimental manipulation 1, 2
Clinical Context
The evidence base examining TV viewing and health outcomes predominantly uses cohort designs, as referenced in multiple systematic reviews of observational studies 5. These studies follow populations with different TV-watching patterns to assess associations with various health outcomes over time, which is precisely the design described in this question 5.