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Unformatted text preview: Midterm 2  Form A  Spring 2010 Economics 203 Instructors: Petry and Sahakyan Name: 1. B. A positive residual is more likely to follow a positive residual when positive autocorrelation is present. Similarly, a negative residual is more likely to follow a negative residual when positive autocorrelation is present. In contrast, negative autocorrelation is characterized by adjacent residuals being likely to be of opposite signs. 2. D. R 2 of 0 means your SSR is 0 (with SST =50,000). That means your Fstatistic is 0, since it has SSR on top and something positive on bottom. 3. A. The pvalues for estimated coefficients are always twotailed ( 6 =). The pvalue of 0.000402 is for the estimated coefficient b 1 yet hypotheses are always on the population parameters, thus β 1 . 4. A. The test implied by the Excel output is the twosided test. To get the pvalue for the onesided test, we halve the pvalue from the twosided test. 5. C. The predicted sales is ˆ SALES = 8 . 7+5(4 . 2) = 29 . 7. The appropriate critical value is t . 025 , 8 = 2 . 31. This gives everything that we need to put into the confidence interval formula: ˆ SALES ± t α/ 2 s ε s 1 /n + ( x g ¯ x ) 2 ( n 1) s 2 x = 29 . 7 ± (2 . 31)(3 . 234578798) s 1 / 10 + (5 5) 2 (10 1)2 . 22 = 29 . 7 ± (2 . 31)(3 . 234578798) p 1 / 10 = (27 . 337 , 32 . 063) 6. C. The SST for model 1 is SSE 1 + SSR 1 = 432 + 123 = 555. Since the models are applied to the same data, SST 2 = 555 also. Then SSE 2 = SST 2 SSR 2 = 555 100 = 455. 7. C. ¯ R 2 1 = 1 SSE 1 / ( n 1 k 1 1) SST 1 / ( n 1 1) = 1 432 / (200 5 1) 555 / (200 1) = 0 . 2016 ¯ R 2 2 = 1 SSE 2 / ( n 2 k 2 1) SST 2 / ( n 2 1) = 1 455 / (200 3 1) 555 / (200 1) = 0 . 1676 8. C. The partial F statistic is: F = ( SSR f SSR r ) /k d MSE f = ( SSR 1 SSR 2 ) / 2 MSE 1 = (123 100) / 2 432 / (200 5 1) = 5 . 164 9. A. The divisor in the numerator is 2, so the numerator (first) degrees of freedom is 2. The divisor in the denominator is 194, so the denominator (second) degrees of freedom is 194....
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This note was uploaded on 02/14/2011 for the course ECON 203 taught by Professor Petry during the Spring '09 term at University of Illinois, Urbana Champaign.
 Spring '09
 PETRY
 Economics

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