stat425pracexam2

# stat425pracexam2 - 1 A highway data set contains the number...

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1. A highway data set contains the number of deaths per million vehicle miles from the year 1945 to 1984 for the entire United States and the state of New Mexico. A Linear regression analysis is conducted. The R output is given below where predictor Year is coded as 1, 2, … 40 corresponding to year 1945, year 1946, …year 1984. (a) What is the X matrix in the linear regression analysis reported in R output. X= 1 1 0 0 1 2 0 0 ┊┊ ┊┊ ┊┊ ┊ ┊ 1 40 0 0 1 1 1 1 1 2 1 2 ┊┊ ┊┊ ┊┊ ┊ ┊ 1 40 1 40

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(b) What are the estimated trends? In which year do we expect the death rate for New Mexico to be equal to the death rate for the United States? The estimated trend for New Mexico is Y NM = 13.15385-0.23616 Year The estimated trend for United States is Y US = 13.15385-4.41692+(0.07778-0.23616)Year = 8.73693-0.15838 Year When the two death rate are equal, we need to slove the equation Y NM = Y US 13.15385-0.23616 Year = 8.73693-0.15838 Year Year=56.79 57 1945+57-1=2001 Therefore, in the year 2001, the death rate are supposed to be equal. (c) State the null and alternative hypotheses for the test based on the reported F- statistic, 310 : 4 on 3 and 76 degrees of freedom . For the linear regression model, Y=X β +e, E(e)=0,Var(e)= 2 80 I σ The null and alternative hypothesis are: Ho: 1 2 3 0 = = = Ha: at least one of them is not equal to zero (d) Compute the predicted death rate for both New Mexico and the United States in 1985. Year=1985+1-1945=41
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## This note was uploaded on 12/12/2010 for the course STAT 425 taught by Professor Ma,p during the Fall '08 term at University of Illinois, Urbana Champaign.

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stat425pracexam2 - 1 A highway data set contains the number...

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