Logistic Regression: A Self-learning Text, Third Edition (Statistics in the Health Sciences)

Recall that the previously shown output gave Wald statistics for HEAD, AGECAT, and FLEX that were nonsignificant. A backward eli ...

Note, however, if two models that are not nested are compared, there is no guarantee which model will have a larger AUC. For exa ...

VI. SUMMARY DP¼discriminatory performance of a binary logistic model Good DP:model discriminates casesðY¼ 1 Þfrom noncasesðY¼ 0 ...

We suggest that you review the material cov- ered in this chapter by reading the detailed outline that follows. Then do the prac ...

Detailed Outline I. Overview (pages 348–350) A. Focus: how to assess discriminatory performance (DP) of a binary logistic model. ...

 Se and 1Sp both focus on predicted cases  If good discrimination, would expect Se> 1 Sp for allcp C. Pick a case and a n ...

IV. Computing the Area Under the ROC (pages 358–365) A. General formula: AUC¼ no:of case=noncase pairs in whichP^ðXcaseÞ^PðXnon ...

D. Logistic Model: logit PðXÞ¼b 0 þb 1 FLEXþb 2 WEIGHT þb 3 AGECATþb 4 HEAD þb 5 PATELLAR E. Results based on SAS’s LOGISTIC pro ...

Practice Exercises The following questions and computer information con- sider the Evans Country dataset on 609 white males that ...

Classification Table (continued) Correct Incorrect Percentages Prob Level Event Non- event Event Non- event Correct Sensi- tivit ...

e. Notice for this data, as the cut-point gets larger the specificity also gets larger (or stays the same). For example, a cut-p ...

Test The following questions and computer output consider a data from a cross-sectional study carried out at Grady Hospital in A ...

Classification Table Correct Incorrect Percentages Prob Level Event Non- event Event Non- event Correct Sensi- tivity Speci- fic ...

For a discrimination cut-point of0.300in the Classifi- cation Table provided above, a. fill in the table below to show the cell ...

Sensitivity1.0 0.8 0.6 0.4 0.2 0.0 0.0 0.2 0.4 0.6 0.8 1.0 1 – specificity The ROC curve obtained for the model fitted to these ...

a. What is the area within the entire rectangle and what does it have in common with the formula for the area under the ROC curv ...

coincide with your answer to question 3b in terms of the discriminatory power of the fitted model? c. Suppose the distribution o ...

Answers to Practice Exercises a. X¼(CAT¼1, AGE¼50, CHL¼200, ECG¼0, SMK¼0, HPT¼0) P^ðXÞ¼ 1 =f 1 þexp½logitP^ðX*ފg, where logi ...

d. AUC¼c¼ wþ 0 : 5 z np ¼ 38,198ð: 786 Þþ 0 : 5 ð38,198Þð 0 : 005 Þ 38,198 ¼ 0 : 789 e. The AUC for the no interaction model is ...

11 Analysis of Matched Data Using Logistic Regression n Contents Introduction 390 Abbreviated Outline 390 Objectives Presentatio ...