A Brief Introduction to Epidemiology - VI (Basics of Research & Epidemiological Research Methodologies)

1. A Brief Introduction to Epidemiology - VI (Basics of Research & Epidemiological Research Methodologies) Betty C. Jung, RN, MPH, CHES

2. 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

3. Performance Objectives • Basic 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

4. 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.

5. What is Research? • Traditionally, the Scientific Method means: • Control of variables and biases • Use of empirical evidence to generate knowledge • Generalizable results

6. The Scientific Method • Describe phenomena • Explore relationships among phenomena • Explain phenomena and increase understanding • Predict causes of and relationships among phenomena • Control phenomena

7. 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

8. Steps in Performing Research • Research Problem • Literature Review • Conceptual & Theoretical Frameworks • Variables & Hypotheses • Research Design • Population & sample • Data Collection • Data Analysis • Results and findings

9. 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

10. 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

11. Categorizing Research • Qualitative & Quantitative Research • Basic & Applied Research • Patton’s Research Typology

12. Words or Numbers • Qualitative Research - data from words, pictures, etc. • Quantitative Research - data from numbers

13. 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

14. The Continuum of ResearchA Typology (Patton) • Basic Research • Applied Research • Summative Evaluation • Formative Evaluation • Action Research

15. 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.?

16. 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.?

17. 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.?

18. 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?

19. 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?

20. 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)

21. Research Designs in Analytic Epidemiology • Cohort Study • Case-Control Study • Data from Entire Population • Ecologic Designs

22. 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

23. 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

24. 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)

25. Measures of Association:Difference Measures • Two Independent Means • Two Independent Proportions • The Attributable Risk

26. 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

27. Measures of Association:Ratio Measures • Relative Risk (RR) • Relative Prevalence (RP) • Odds Ratio (OR)

28. 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 <0.01 >10.0 Approaching Infinity Source: Handler,A, Rosenberg,D., Monahan, C., Kennelly, J. (1998) Analytic Methods in Maternal and Child Health. p. 69.

29. 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

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