How are analytic (explanatory) studies different from descriptive studies?

• A. Exposure and outcome are measured and thus associations between the two can be made statistically
• B. They do not measure exposures
• C. They cannot perform statistical analysis
• D. They always use randomization

Answer: (A)

Analytic (explanatory) studies are designed to test hypotheses about whether an exposure is associated with an outcome and to quantify that association using statistics. This requires collecting data on both the exposure and the outcome and applying statistical methods to estimate measures of association (like risk, odds, or rate ratios) and to adjust for potential confounding. Descriptive studies, by contrast, focus on describing how often or where a disease or outcome occurs, and who is affected, without testing whether an exposure is related to the outcome.

That’s why the statement that exposure and outcome are measured and associations between the two can be tested statistically best captures what analytic studies do. The other statements are inconsistent with analytic design: they may measure exposures, they can perform statistical analysis, and randomization is not required—many analytic studies are observational and do not randomize.