Research Methodologies
Types of Study Designs
Faculty Name : Dr. Shivani Chowdhury Salian
Basic Epidemiology
Study Designs in Epidemiologic
Research
Fundamental Assumption in
Epidemiology
• Disease doesn’t occur in a vacuum
 Disease is not randomly distributed
throughout a population
– Epidemiology uses systematic approach to
study the differences in disease distribution
in subgroups
– Allows for study of causal and preventive
factors
Components of Epidemiology
• Measure disease frequency
– Quantify disease
• Assess distribution of disease
– Who is getting disease?
– Where is disease occurring?
– When is disease occurring?
Formulation of hypotheses concerning causal
and preventive factors
• Identify determinants of disease
– Hypotheses are tested using epidemiologic studies
Types of primary studies
• Descriptive studies
– describe occurrence of outcome
• Analytic studies
– describe association between
exposure and outcome
Basic Question in Analytic Epidemiology
• Are exposure and disease linked?
Exposure
Disease
Basic Questions in Analytic Epidemiology
• Look to link exposure and disease
–What is the exposure?
–Who are the exposed?
–What are the potential health effects?
–What approach will you take to study
the relationship between exposure and
effect?
Wijngaarden
Basic Research Study
Designs and their
Application to Epidemiology
Big Picture
• To prevent and control disease
• In a coordinated plan, look to
– identify hypotheses on what is related to
disease and may be causing it
– formally test these hypotheses
• Study designs direct how the
investigation is conducted
What designs exist to
identify and investigate
factors in disease?
Descriptive
Case report
Case series
Descriptive
Epidemiology
Analytic
RCT
Cohort study
Case-Control
study
Case-Crossover
study
Cross-sectional
study
Before-After
study
Ecologic study
Timeframe of Studies
• Prospective Study - looks forward,
looks to the future, examines future
events, follows a condition, concern or
disease into the future
time
Study begins here
Timeframe of Studies
• Retrospective Study - “to look back”,
looks back in time to study events that
have already occurred
time
Study begins here
Study Design Sequence
Hypothesis formation
Case reports
Case series
Analytic
epidemiology
Clinical
trials
Descriptive
epidemiology
Animal
study
Hypothesis testing
Cohort
Casecontrol
Crosssectional
Lab
study
Increasing Knowledge of
Disease/Exposure
Descriptive Studies
Develop
hypothesis
Case-control Studies
Investigate it’s
relationship to
outcomes
Cohort Studies
Define it’s meaning
with exposures
Clinical trials
Test link
experimentally
TYPES OF RESEARCH
&
RESEARCH DESIGNS
Types of Study Design:
• There is no best type of study design
• The context, assumptions, paradigms
and perspectives decide the type of
research methodology
How to Choose a Research Design
•
•
•
•
Does it adequately test the hypothesis?
Does it identify & control extraneous factors?
Are results generalizable?
Can the hypothesis be rejected or retained via
statistical means?
• Is the design efficient in using available resources?
Selecting a Research Design
1.
2.
3.
4.
5.
6.
7.
8.
Level of knowledge
Nature of the research phenomenon
Nature of the research purpose
Ethical considerations
Feasibility
Validity and availability of data
Precision
Cost
Anatomy of Research
1. Define the problem ( Characteristics)
2. Specify the objectives (Hypothesis)
3. Select design or type of study
4. Select study population
5. Collect data
6. Analyze data
7. Determine conclusions
Select design or type of study
Increasing Knowledge of
Disease/Exposure
Descriptive Studies
Develop
hypothesis
Case-control Studies
Investigate it’s
relationship to
outcomes
Cohort Studies
Define it’s meaning
with exposures
Clinical trials
Test link
experimentally
Types of Research
From the view point of
Application
Pure
Research
Applied
Research
Objectives
Type of Information
Sought
Exploratory
Research
Quantitative
Research
Descriptive
Research
Qualitative
Research
Correlation
Research
Explanatory
Research
TYPE OF STUDIES
Observational
1. Correlational study
2. Case reports and case series
3. Cross sectional survey
4. Case-control study
5. Cohort study
Experimental
1. Community trials
2. Clinical trials – individuals
Study Designs
1.
2.
3.
4.
5.
6.
Descriptive Studies
Cross-Sectional Studies
Cohort Study
Case Control
Randomized Controlled Trials
Survey Research
Critical Thinking Decision Path:
Non-experimental Design Choice
-
Case study
Cross-sectional
Longitudinal
Etc.
-
Cross-sectional
Case control
Cohort
Etc
True-Experiment
Quasi-experimental
Pre-experimental
Analytical
Descriptive
Explorative
Health Sciences and Nursing Research
Non-interventional
Interventional
-
Note: CRD-complete random design, RBD-random block design, FD- factorial design
CRD
RBD
FD
etc
4 Types of Research
•
•
•
•
Basic research
Applied research
Action research
Evaluation research
Basic Research
• Also known as fundamental research (sometimes pure
research) is research carried out to increase
understanding of fundamental principles.
• Many times the end results have no direct or
immediate commercial benefits
• Basic research can be thought of as arising out of
curiosity.
• However, in the long term it is the basis for many
commercial products and applied research.
• Basic research is mainly carried out by universities
Applied Research
• Concern with addressing problem of the world as
they are perceived by participants, organization or
group of people
• Action oriented and aims to assess, describe,
document or inform people concerned about the
phenomenon under investigation
• Findings are intended to have immediate and
practical value
• In the field of education, policy, evaluation and
contract are all examples of applied research
Action Research
Action Research is simply a form of self-reflective
enquiry undertaken by participants in social
situations in order to improve the rationality and
justice of their own practices, their understanding of
these practices, and the situations in which these
practices are carried out.
Wilf Carr and Stephen Kemmis (1986)
Evaluation research
• Major concern is practical application
• Tends to be viewed as an isolated case study though
the methodologies may be transferable
• Rooted in values and politics
• Is immediately prescriptive based upon logic and
experience
• Reports are written for implementers, users and other
interested people
• The extent of dissemination is controlled by sponsor
RESEARCH DESIGNS
QUANTITATIVE
•
•
•
•
Experimental study
Quasi-experimental
Survey study
Correlational study
QUALITATIVE
• Ethnography
• Case study
• Historical study
Thank You