quiz02.sp01

quiz02.sp01 - Quiz 2, Dickey St 512, Spring 20001 All...

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Sheet1 Page 1 Quiz 2, St 512, Spring 20001 Dickey All questions refer to this situation: I have n=12 back stress measurements Y, one for each of 12 subjects. Each subject was asked to lift a box onto a shelf. My explanatory variables that varied from subject to subject are H = shelf height in feet and W = box weight in pounds and I am assuming a model of the form Y = beta_0 + beta_1 H + beta_2 W + e Where I assume each ei has a normal distribution with mean 0 and unknown common variance. As in our class example, I ran PROC REG where STRESS is my Y variable. On the last page (tear it off if you like) is part of the output. Questions: (a) (6 pts.) What, if any, other assumptions are made about the errors e? (b) (6 pts.) How many rows ___ and columns ____ does my regression X matrix have? (c) (8 pts.) What is the rank (a number) of my regression X matrix? ______ (d) (6 pts.) How many error degrees of freedom _____ do I have? (e) (12 pts.) Write down the equation that I would use to predict stress (Y) for a given W and H ^ Y = _____________________________________ and give the predicted value of back stress ________ for lifting a 30 pound box onto a shelf at height 5 1/2 feet. (f) (8 pts.)

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This note was uploaded on 08/01/2008 for the course ST 512 taught by Professor Dickey during the Summer '07 term at N.C. State.

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quiz02.sp01 - Quiz 2, Dickey St 512, Spring 20001 All...

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