A Brief Introduction to Epidemiology VI Basics of Research

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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 understanding of
• The Scientific Method
• Different types of research
• Pattons Research Typology
• Research designs used in Epidemologic Research
• Common measures used in Epidemiologic Research

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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
  peoples perceptions
• Nature has order, regularity, and consistency
• All phenomena have causes that can be discovered

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Steps in Performing Research

• Research Problem
• Literature Review
• Conceptual Theoretical Frameworks
• Variables Hypotheses
• Research Design
• Population sample
• Data Collection
• Data Analysis
• Results and findings

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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
• Pattons 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 ResearchA 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 As 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 As Community Zs 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 AssociationDifference 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 AssociationRatio 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 1.0-1.2 None
• 0.67-0.83 1.2-1.5 Weak
• 0.33-0.67 1.5-3.0 Moderate
• 0.10-0.33 3.0-10.00 Strong
• lt0.01 gt10.0 Approaching
  Infinity
• Source Handler,A, Rosenberg,D., Monahan, C.,
  Kennelly, J. (1998) Analytic Methods in Maternal
  and Child Health. p. 69.

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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
• N

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References

• For Internet Resources on the topics covered in
  this lecture, check out my Web site.