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Chapter 10

Chapter 10. Interpreting Results. Learning Objectives. Interpret the results of basic computer printout correctly Translate computer printout into reportable results Address unanticipated results Interpret study results correctly Interpret study results ethically.

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Chapter 10

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  1. Chapter 10 Interpreting Results

  2. Learning Objectives • Interpret the results of basic computer printout correctly • Translate computer printout into reportable results • Address unanticipated results • Interpret study results correctly • Interpret study results ethically

  3. “There are three kinds of lies: lies, damned lies, and statistics.” • Unethical, misleading, and perhaps harmful to interpret study results inaccurately

  4. Example Analysis • Hypothesis: there is a positive relationship between parents’ health history and subjects’ health status • Cross-section survey data set with 100 adult subjects from a mid-sized Midwest City and 50 variables about health status, parents’ health history, health-related behaviors, and demographic characteristics

  5. Variables • Independent: parents’ health history measured as an additive scale combining all negative health events and risk behavior such as cigarette smoking, diabetes, heart disease, and so on • Dependent: subjects’ own health status measured as an additive scale combining relevant negative health measures such as high fat diet, high blood pressure, high total cholesterol, high blood sugar, and so on • Confounder: Gender

  6. Step 1: Get to Know Variables ProcUnivariate Moments N 100 Sum Weights 100 Mean 52.775 Sum Observations 5278 Std Deviation 18.9571720 Variance 179.687180 Skewness -0.4820386 Kurtosis -0.7502476 Uncorrected SS 574919 Corrected SS 17878.875 Coeff Variation 17.9603714 Std Error Mean 1.3404744   Basic Statistical Measures Location Variability Mean 52.77500 Std Deviation 18.95717 Median 54.00000 Variance 179.69718 Mode 59.00000 Range 36.00000 Interquartile Range 14.50000

  7. So far so good

  8. Step 2: Examine Relationships Proc CORR • Variables: risk health female Simple Statistics Variable N Mean StdDev Sum Minimum Maximum Label risk 100 52.23000 20.50588 5278 28.00000 76.00000 family risk score health 100 52.77500 18.95717 5226 31.00000 67.00000 health score female 100 0.54500 0.49922 59.00000 0 1.00000  Pearson Correlation Coefficients, N = 100 Prob > |r| under H0: Rho=0 risk health female risk 1.00000 0.0628 -0.05308 family risk score 0.3889 0.4553 health 0.0628 1.00000 -0.25649 health score 0.3889 0.0273 female -0.05308 -0.25649 1.00000 0.4553 0.0273

  9. Unexpected Result! • Is there enough statistical power? • Is the measure of family risk (and even own health risk) valid? • Are the measures too complex in terms of including multiple dimensions that don’t really cluster together? • Is there anything interesting and worth pursuing?

  10. Step 3: Examine the Multivariable Model ProcReg Analysis of Variance Sum of Mean Source DF Squares Square F Value Pr > F Model 2 318.43003 159.21500 3.10 <.05 Error 97 4981.88963 51.35968 Corrected Total 99 5300 Root MSE 7.16656 R-Square 0.1896 Dependent Mean 51.85000 Adj R-Sq 0.1734 CoeffVar 13.82171

  11. Step 3 (cont.) ProcReg (cont.) Parameter Estimates Parameter Standard Variable Label DF Estimate Error t Value Pr > |t| Intercept Intercept 1 12.32529 3.19356 3.86 0.0002 risk parent risk score 1 0.19465 0.28645 1.12 0.3061 female 1 -2.69998 1.02272 -2.64 0.0098 Parameter Estimates Variable Label DF 95% Confidence Limits Intercept Intercept 1 0.32529 24.32529 risk parent risk score 1 -0.48111 0.91800 female 1 -1.67708 -3.72252

  12. Step 4: Present the Data Table 1. Example Presentation of Descriptive Statistics --- data not presented Note: The measure for gender (Female) is coded 0 for males and 1 for females.

  13. Step 4 (cont.) Table 2. Example Presentation of Pearson Correlation Coefficients *p<0.05 Note: The measure for gender (Female) is coded 0 for males and 1 for females.

  14. Step 4 (cont.) Table 10.3 Example Presentation of Multiple Regression Results *p<0.05 Note: The measure for gender (Female) is coded 0 for males and 1 for females.

  15. Step 5: Answer the Research Question • Is there a relationship between parents’ health problems and subjects’ health status? • Yes and no • Complex relationship • Go back to the literature • Evidence of a multidimensional aspect of family risk? • Consider and discuss the study limitations

  16. Has there been a contribution to the scientific method?

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