The document discusses different study designs used in epidemiology. There are three main types of study designs: descriptive studies which quantify the magnitude and distribution of health problems; analytical studies which compare groups to identify causes and risk factors; and experimental studies which assess the efficacy of interventions. Descriptive studies include case reports, case series, and cross-sectional studies. They are used for health care planning and identifying trends but cannot determine causation. Analytical studies include cohort and case-control studies while experimental studies involve randomized controlled trials. The choice of study design depends on existing knowledge, the objectives of the study, and available resources.

1. Study Designs
Dr. Win Aye Hlaing
Lecturer
Department of Epidemiology
University of Public Health, Yangon

2. Choice of Study Design
The choice of study design is mainly
determined by:
• Existing knowledge about the problem
• Objective of the study
• Available resources

3. Knowledge Status
• Knowledge about the magnitude and
distribution of the health problem
• Knowledge about the causes of the health
problem
• Knowledge about the solutions for the health
problem

4. Objective & Study Design
Objective Study Design
To quantify the magnitude and
distribution
Descriptive
To compare groups to elicit the
causes/risk factors
(association)
Analytical
To assess the efficacy of drugs,
treatments, interventions
Experimental

5. Study Design
• Observational (Non-Experimental) Study
– Descriptive Studies
• Case Report
• Case Series
• Cross-sectional descriptive Study
– Analytic Studies
• Cohort Studies
• Case-control Studies
• Cross-sectional Comparative/Analytic Studies
• Experimental Study
– Randomized Control Trial
– Clinical Trial
– Field Trial

6. Descriptive Studies
A Descriptive study is designed to describe the
distribution of variables by time, place and
person by making all measurements on a
single occasion

7. Types of Descriptive Study
• Case Report
• Case Series
• Cross-sectional Study

8. Uses of Descriptive Studies
• Health Care Planning
(prioritization, target population & resource
allocation)
• Trend Analysis
(Secular trend, Cyclic changes, Seasonal variation &
Epidemics)
• Clues about Cause

9. Advantages of Descriptive Studies
• Available data (often)
• Relatively quick and inexpensive

10. Disadvantages of Descriptive Studies
• Lack of temporality between exposure and
outcome
• Difficult to use to assess causation (outcome may
have affected “exposure”)

11. THANK YOU!!
6/26/2017 11