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Unformatted text preview: Stats for Strategy Fall 2008 HOMEWORK 10 (covers Topic 11 and Topic 12, Part 1. Due Monday, Dec. 1) DIRECTIONS: • Part of this assignment requires reading in the supplementary textbook Chapter 17: Logistic Regression. Find this chapter as a PDF file on the main course webpage. • Some of the exercises listed below include special instructions which modify or clarify textbook instructions. • Data sets for some exercises are available on the Data Sets link from the course website. (Remember to open data files as worksheets in MINITAB .) Homework Part 1: Topic 11 (Logistic Regression) A. MailOrder Sales • Open the PDF file for the supplementary textbook Chapter 17: Logistic Regression on the main course webpage. Read the description of mailorder sales on the first page. Answer these questions: (a) There are 5 predictor variables and a response variable described for this logistic regression. Let’s call them x 1 , x 2 , x 3 , x 4 , x 5 , and y . Write an English definition for all 6 variables, including the meaning of “0” and “1” for binary variables. (b) Which of the variables are binary ? Which are quantitative (i.e., numerical )? B. College Student Drinking • The textbook introduces logistic regression with the same data on drinking as used in Example 2 of the Topic 11 notes. Quickly glance over the notes you wrote for Example 2 on pages 811 of the Topic 11 notes. • Now open page 172 of the textbook Chapter 17 PDF file. Read pages 172 and 173 at a leisurely pace. Soak up what the textbook says and occasionally glance at the Topic 11 notes to confirm that the book’s answers are the same as ours. • Next read Model for logistic regression at the bottom of page 174 and all of page 175. Then read Fitting and interpreting the logistic regression model on pages 176 and 177. Pay particular attention to the way the book calculates b and b 1 at the top of 177. Are these the same estimates (except for rounding) that MINITAB logistic regression produces in the output shown on page 9 of the Topic 11 notes? • Lastly, read Section 17.1 Summary at the bottom of page 174 and top of page 175. • Open MINITAB and type the drinking data into the worksheet: C1 C2 C3 C4 Gender Binge Total Men 1 1630 7180 Women 1684 9916 1 • Reproduce the MINITAB output shown on page 9 of the Topic 11 notes. (Recall that in class we made some corrections to the Minitab instructions shown in the notes.) Here are the correct MINITAB steps: Stat > Regression > Binary Logistic Regression > (Click radio button “Response in event/trial format”) > (Enter Binge for Number of events, Total for Number of trials) > (Select all predictor variables for the Model : Gender ) > (Select all binary predictor variable as Factors : Gender ) > OK Notice that there’s some extra output at the bottom which you can ignore....
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