A Brief Introduction to
Epidemiology - VI
(Basics of Research &
Epidemiological Research
Methodologies)
Betty C. Jung, RN, MPH, CHES
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Learning Objectives
To
understand:
– The proper methods for conducting
research
– What makes for good research design
– The pitfalls of poor research design
– The basics of epidemiological
research design
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Performance Objectives
Basic
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understanding of :
– The Scientific Method
– Different types of research
– Patton’s Research Typology
– Research designs used in
Epidemologic Research
– Common measures used in
Epidemiologic Research
Introduction
The primary purpose of research is to
conduct a scientific, or, scholarly
investigation into a phenomenon, or
to answer a burning question.
Research is defined as a systematic
approach to problem solving.
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What is Research?
Traditionally,
the Scientific
Method means:
– Control of variables and biases
– Use of empirical evidence to
generate knowledge
– Generalizable results
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The Scientific Method
Describe
phenomena
Explore relationships among
phenomena
Explain phenomena and increase
understanding
Predict causes of and relationships
among phenomena
Control phenomena
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Assumptions for Scientific Method
Objective
reality exists independent
from people’s perceptions
Nature has order, regularity, and
consistency
All phenomena have causes that can
be discovered
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Steps in Performing Research
 Research
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Problem
 Literature Review
 Conceptual & Theoretical Frameworks
 Variables & Hypotheses
 Research Design
 Population & sample
 Data Collection
 Data Analysis
 Results and findings
What is a Pilot Study?
Done
before a major study begins
Minimizes the possibility of having
significant difficulties occurring in
during the major study
Obtain info for improving the major
study
Make revisions before beginning the
major study
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Limitations of Research
Based on the Scientific Method
Every
research study has flaws
No single study proves or disproves
a hypothesis
Ethical issues can constrain
researchers
Adequate control is hard to
maintain in a study
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Categorizing Research
Qualitative
& Quantitative
Research
Basic & Applied Research
Patton’s Research Typology
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Words or Numbers
Qualitative
Research - data from
words, pictures, etc.
Quantitative Research - data
from numbers
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Basic & Applied
Basic
Research - undertaken to
advance knowledge in a given area understanding relationships among
phenomena
 Applied Research - undertaken to
remedy a particular problem or
modify a situation - to make
decisions or evaluate techniques
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The Continuum of Research
A Typology (Patton)
Basic
Research
Applied Research
Summative Evaluation
Formative Evaluation
Action Research
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Basic Research
Goal:
To understand & explain
Discipline-specific
Contribution: A theory to explain
the phenomenon under investigation
Question: How did the West Nile
Virus spread to the U.S.?
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Applied Research
Goal:
To understand societal problems and
identify potential solution
Takes an explanation and apply it to real-world
problems & experiences
Inter-disciplinary
Contribution: Solutions to real-world problems
Question: How can epidemiologists track the
spread of the West Nile Virus in the U.S.?
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Summative Evaluation
Goal:
To evaluate the effectiveness of
specific interventions for specific
problems under specific conditions
Question: In 2000, did mosquito
spraying contain the spread of the
West Nile Virus in the U.S.?
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Formative Evaluation
Goal:
To improve the effectiveness of
specific programs with the setting
these programs were developed for
Question: Was State A’s mosquito
spraying program equally effective
in the towns that conducted
spraying?
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Action Research
Goal:
To study a specific problem
within a program, or, organization,
or, community
Question: Was State A’s
Community Z’s spraying schedule
effective in reducing the number of
residents infected with the West Nile
Virus?
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Epidemiological Study Designs
Observational
Studies - examine
associations between risk factors and
outcomes (Analytical - determinants and
risk of disease, and descriptive - patterns
and frequency of disease)
Intervention Studies - explore the
association between interventions and
outcomes. (Experimental studies or clinical
trials)
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Research Designs in
Analytic Epidemiology
Cohort
Study
Case-Control Study
Data from Entire Population
Ecologic Designs
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Epidemiologic View of Best
Estimates
Selection
Bias - over-representation of
those who are available to provide it
Survivor Bias - obtaining data only
from those who have survived to
provide it
Measurement biases
– Recall bias
– Reporting bias
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Measures of Association &
Hypothesis Testing
Test Statistic =
Observed Association - Expected Association
Standard Error of the Association
Type
I Error: Concluding there is an
association when one does not exist
Type II Error: Concluding there is no
association when one does exist
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Measures of Association
Two
Main Types of Measures
– Difference Measures (Two
Independent Means, Two
Independent Proportions, The
Attributable Risk)
– Ratio Measures (Relative Risk,
Relative Prevalence, Odds Ratio)
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Measures of Association:
Difference Measures
Two
Independent Means
Two Independent Proportions
The Attributable Risk
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Attributable Risk (AR)
The
difference between 2
proportions
Quantifies the number of
occurrences of a health outcome that
is due to, or can be attributed to, the
exposure or risk factor
Used to assess the impact of
eliminating a risk factor
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Measures of Association:
Ratio Measures
Relative
Risk (RR)
Relative Prevalence (RP)
Odds Ratio (OR)
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Strength of Association
Relative Risk;(Prevalence); Odds Ratio Strength of Association
0.83-1.00
0.67-0.83
0.33-0.67
0.10-0.33
<0.01
1.0-1.2
1.2-1.5
1.5-3.0
3.0-10.00
>10.0
None
Weak
Moderate
Strong
Approaching
Infinity
Source: Handler,A, Rosenberg,D., Monahan, C., Kennelly, J.
BC Jung(1998) Analytic Methods in Maternal and Child Health. p. 69.
The Preventive Fraction
 The
2x2 table does not always have to be organized in
terms of a risk factor and adverse outcome. Can be
organized to focus on a protective effect. Useful for
program evaluation, where a program has been
designed to have a positive impact and measuring the
magnitude of this impact is desired.
 A measure
of program effectiveness.
Adverse Outcome
Y
N
Program Y
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N
References
For
Internet Resources on the
topics covered in this lecture,
check out my Web site.
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