A(n) _______________________ groups the study populations by exposure versus nonexposure to a certain risk factor to see if either group develops the outcome in question.
a. Experimental study
b. Case report
c. Cross-sectional study
d. Correlation study
e. Observational study

Verified step by step guidance

1. Step 1: Understand the key terms in the question. The problem asks for a type of study that groups populations based on exposure to a risk factor and then observes if the outcome develops. This implies a comparison between exposed and non-exposed groups over time.
2. Step 2: Review the definitions of each study type: an experimental study involves intervention by the researcher; a case report describes a single case; a cross-sectional study looks at data at one point in time; a correlation study examines relationships between variables without grouping by exposure; an observational study observes subjects without intervention, often grouping by exposure.
3. Step 3: Identify which study type fits the description of grouping populations by exposure and following them to see if the outcome occurs. This is characteristic of observational studies, particularly cohort studies, where subjects are grouped by exposure status and followed over time.
4. Step 4: Recognize that the question is looking for the general category of study that groups by exposure versus non-exposure and observes outcomes, which is an observational study rather than an experimental one.
5. Step 5: Conclude that the correct answer is an observational study, as it matches the description of grouping populations by exposure and monitoring for outcomes without researcher intervention.

Key Concepts

Cohort Study

A cohort study is an observational study design that groups participants based on exposure to a risk factor and follows them over time to observe the development of outcomes. It compares exposed and non-exposed groups to identify associations between risk factors and diseases.

Observational Study

Observational studies involve monitoring subjects without intervention by the researcher. Unlike experimental studies, they do not assign exposures but observe natural variations, making them useful for studying risk factors and outcomes in real-world settings.

Study Design Types in Epidemiology

Understanding different study designs—such as experimental, case report, cross-sectional, correlation, and observational studies—is essential to interpret how data is collected and analyzed. Each design has unique features affecting the strength of evidence and causality inference.