1. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Statistical Methods for Health Care Research Chapter 1 Using Research and Statistics in Health Care

2. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Descriptive –Numerical or graphic summaries of data –Charts, graphs, tables, summary statistics (e.g., mean and standard deviation) Inferential –Statistical techniques that allow conclusions to be drawn about the relationships found among different variables –Examples include Chi-square test, t test, ANOVA. Types of Statistics

3. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Descriptive and Explorative –Simply describe situations and events –Ask descriptive questions “What is the average length of stay in a hospital after being admitted for an asthma attack?” –Descriptive statistics are used to analyze data from these studies. Types of Studies

4. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Explanatory Studies –Elucidate relationships among variables –Ask inferential questions Are women who are sedentary during the 3rd trimester of pregnancy more likely to have a C- section than women who exercise regularly during the 3rd trimester? –Use inferential statistics –May or may not seek to establish causality Types of Studies (cont.)

5. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Prediction and Control –Seek to determine which variables predict other variables and to determine causality –Ask inferential questions Are people who receive an experimental medication less likely to have symptoms of the disease than people who receive the standard medication? –Use inferential statistics Types of Studies (cont.)

6. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins True or False Explanatory studies simply seek to describe situations and events. Question

7. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins False Rationale: Explanatory studies seek to elucidate the relationships among variables. Answer

8. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins 1. Statement of the problem and its significance 2. Theoretical/conceptual framework 3. Research questions to be answered 4. List of hypotheses to be tested 5. Definitions of key terms and variables Ten-Step Study Plan

9. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins 6. Description of the research design 7. Description of the sample and how it was obtained 8. Description of the planned statistical analysis 9. Statement of assumptions and limitations 10. Dissemination plan Ten-Step Study Plan (cont.)

10. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Explain the Purpose of the Study –The research question –Why it is important? –How it fits into the existing body of research? Be Clear and Concise –Clearly state what the study seeks to accomplish –Use phrases like “the purpose of this study is to…” Statement of Problem

11. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins All studies need an underlying framework that organizes the analysis. –Draw from existing theory or provide a logic model –Use the framework to organize your research questions and hypotheses –Use existing theoretical models where possible and cite appropriately Theoretical/Conceptual Framework

12. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Research questions should stem directly from the statement of the purpose of the study. –Ground questions in theory and current literature –Be clear about the expected relationships –Relate directly to the data that will be gathered by the researcher Research Questions

13. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins A hypothesis is a tentative prediction or description of the expected relationship between two or more variables. Hypotheses translate research questions into statements that can be tested with inferential statistics. There are two types of hypotheses: directional and nondirectional. List of Hypotheses to be Tested

14. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Directional (one-way) hypotheses state the expected direction of the relationship between the two variables: –People who are immunized will be less likely to contract the flu than people who are not immunized. Nondirectional (two-way) hypotheses simply state that there will be a relationship between the variables: –There will be a relationship between obesity and exercise level. List of Hypotheses to be Tested (cont)

15. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Define all terms that may be unclear to the reader Write out all acronyms the first time they are used Define all variables Indicate whether the variables are dependent, independent, or covariates Definitions of Key Terms and Variables

16. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Independent variables are those that are manipulated and/or may affect the outcome of interest. These typically include age, gender, and ethnicity. Dependent variables are the outcomes of interest. –These typically include health status, use of health services, and cost of care. Definitions of Key Terms and Variables (cont.)

17. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins True or False Descriptive studies do not need a framework. Question

18. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins False Rationale: All studies need to be organized using a theoretical or conceptual framework. Answer

19. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Describe how the data will be or were collected. –Describe the type of study (observational, longitudinal, quasi-experimental, experimental) –Describe the way in which the data will be gathered (interview, survey, medical records, etc.) –If secondary data analysis, describe the study that provided the data and provide a citation for the study Description of the Research Design

20. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Describe the sample –Type of sampling (random, nonrandom) –Sample size (overall and of each comparison group) –Sociodemographics (age/gender/ethnicity/education/marital status, other relevant variables) Describe the Sample

21. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Explain how you plan on analyzing the data –How will you clean the data (e.g., make sure it is error free)? –What descriptive statistics will you use? –What inferential statistics will you use? –What type of models will you build (e.g., linear regression, logistic regression, ANOVA, others)? Describe the Statistical Analysis

22. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Assumptions –Statements that are taken to be true even though you have no direct evidence about whether or not they are true –For example, in a study of exercise behavior, we assume that study participants are honest with us when they tell us how frequently they exercise. Assumptions, Limitations, and Delimitations

23. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Limitations –Weaknesses of the study that may limit the validity of the results –Common limitations include small sample sizes, poor response rates, poor follow-up response rates, and lack of random selection. Assumptions, Limitations, and Delimitations (cont.)

24. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Delimitations –Boundaries to which the study was deliberately confined –For example, the study may focus on adults only, on a certain age group only, or on women only. –The delimitations limit the generalizability of the study. Assumptions, Limitations, and Delimitations (cont.)

25. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Dissemination is the way in which the results of the study are shared with others. –Internal reports –Presentations at conferences –Publications in trade journals –Publications in peer-reviewed journals Dissemination Plan

26. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Which of the following is an example of an assumption of a study? A.The self-reported body weight was accurate. B.Only women ages 18 to 34 were included in the study. C.The response rate to the survey was only 33%. D.All of these are assumptions. Question

27. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins A. The self-reported body weight was accurate. Rationale: We would assume that our subjects correctly reported their body weight. Option B is a delimitation and option C is a limitation. Answer

28. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins End of Presentation