Study Types

Question 1

Clinical trial

Answer 1

Two groups. Treatment and control. Randomization and blinding provide for best results.

Question 2

Cohort (longitudinal)

Answer 2

Data collected from a defined group of people (cohort). Look forward or backward in time from intervention to an outcome. Can be prospective or retrospective.

Looking for disease in relation to exposure.

Buzzwords: “Relative risk,” “Incidence”

Question 3

Case-Control

Answer 3

Look backward in time. Pt’s who already have condition (cases) are compared with those who do not (controls) for possible exposure, intervention or risk factor.

Buzzword: “Odds ratio”

Question 4

Cross sectional

Answer 4

Subjects sampled at a fixed point or period of time. Presence or absence of risk factors investigated. SNAPSHOT IN TIME.

Question 5

Ecologic

Answer 5

Disease rates and exposure measured in each of a series of populations (not individuals) and their relation examined.

Looking for correlations

Question 6

Case series/Case reports

Answer 6

Descriptive observations that have occurred in patient or a series of patients.

Question 7

Meta-Analysis

Answer 7

Systematic review using statistical methodology. Pooling data from individual studies as if one study.

Question 8

Systematic review

Answer 8

Summarization of data from multiple studies. Very thorough.