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Unformatted text preview: STA 3024 Practice Exam 3 Name: UFID: • On your scantron, bubble your name, UFID, and exam form. There are no special codes. • A formula sheet, F table, and t table are provided on the last page. I promise not to cheat on this exam. I understand that accessing notes programmed into my calculator constitutes cheating. I also promise not to share information about the exam with people who haven’t taken it yet. Signature: 1. In a multiple regression with two explanatory variables, X 1 and X 2 , the regression t test for X 1 yields a pvalue of 0.005. Using α = 0 . 05, we (A) fail to reject H and conclude that it’s reasonable that Y does not depend on X 1 , provided we hold X 2 constant. (B) fail to reject H and conclude that Y depends on X 1 , provided we hold X 2 constant. (C) reject H and conclude that it’s reasonable that Y does not depend on X 1 , provided we hold X 2 constant. (D) reject H and conclude that Y depends on X 1 , provided we hold X 2 constant. 2. Two researchers both intend to conduct the same multiple regression analysis using three ex planatory variables. They conduct their studies using the same procedures and measure their variables in the same units. The only difference is that Researcher I takes a sample of 32 sub jects, while Researcher II takes a (different) sample of 50 subjects. Which researcher would probably obtain a larger value of SS Res ? (A) Researcher I (B) Researcher II (C) The two researchers’ values of SS Res would probably be equal. (D) The two researchers’ values of SS Res would probably be different, but we can’t say which one would probably be larger. 3. A multiple regression yields the following regression equation: ˆ Y ( X 1 ,X 2 ) = 0 . 14 + 24 . 4 X 1 5 . 8 X 2 . Y is measured in centimeters, X 1 is measured in minutes, and X 2 is measured in kilograms. How should the number 24 . 4 in the regression equation be interpreted? (A) The number 24 . 4 should not be assigned any interpretation. (B) If X 1 is held constant and X 2 is increased by 24.4 kilograms, the predicted value of Y increases by one centimeter. (C) If X 1 is held constant and X 2 is increased by one kilogram, the predicted value of Y increases by 24.4 centimeters. (D) If X 2 is held constant and X 1 is increased by 24.4 minutes, the predicted value of Y increases by one centimeter. (E) If X 2 is held constant and X 1 is increased by one minute, the predicted value of Y increases by 24.4 centimeters....
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 Spring '08
 TA
 Statistics, Linear Regression, Regression Analysis, researcher, Errors and residuals in statistics

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