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Unformatted text preview: Stats for Strategy Fall 2008 HOMEWORK 7 (covers Topic 9, Part 2. Due Monday, Oct. 27) DIRECTIONS: • Some of the exercises listed below include special instructions which modify or clarify textbook instructions. • Use a 5% significance level for tests unless noted otherwise. • 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 .) I. Homework Problems with Posted Solutions (17 textbook exercises) A. Using Population Regression Lines • Exercise 10.3 (p. 577) • Exercise 10.4 B. Research and Development Spending • Exercise 10.5 (p. 579) Helpful hints: * For part (a), make a scatterplot with MINITAB . * For part (b), enter the data into your calculator and use the calculator’s regres- sion function to find the least-squares equation. * For the hand calculations in part (c), use the formula shown on page 27 of the notes for regression sample variance: s 2 = ∑ n i =1 ( y i- b y i ) 2 n- 2 Add more parts to this exercise: (f) Make a Fitted-Line Plot in MINITAB : Stat > Regression > Fitted Line Plot What value does the plot provide for regression standard deviation s ? (Include all available decimal places in your answer.) Is this the same (except for roundoff error) as you calculated by hand in (c)? (g) Find the standard deviation s y for Spending. Does regression on Years reduce the standard deviation for predicting Spending?...
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- Fall '11
- Regression Analysis, Prediction interval, fitted line plot