ex1_2012 - Sociology 63993Exam 1Page 1 Sociology 63993 Exam...

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Unformatted text preview: Sociology 63993Exam 1Page 1 Sociology 63993 Exam 1 February 17, 2012 I. True-False. (20 points) Indicate whether the following statements are true or false. If false, briefly explain why. 1. Cohen and Cohens dummy variable adjustment method is useful when variables like gender or age have missing values. 2. R 2 is biased downwards. 3. The more tolerant a variable is (i.e. the less highly correlated it is with the other IVs), the smaller its unique contribution to R 2 will be. 4. When you have more than one independent variable, random measurement error can cause coefficients to be biased either upward or downward. 5. A Durbin-Watson statistic of 4 or greater indicates that the case is an extreme outlier. II. Short answer. Discuss all three of the following problems. (15 points each, 45 points total.) In each case, the researcher has used Stata to test for a possible problem, concluded that there is a problem, and then adopted a strategy to address that problem. Explain (a) what problem the researcher was testing for, and why she concluded that there was a problem, (b) the rationale behind the solution she chose, i.e. how does it try to address the problem, and (c) one alternative solution she could have tried, and why. (NOTE: a few sentences on each point will probably suffice you dont have to repeat everything that was in the lecture notes.) II-1. . use "http://www.nd.edu/~rwilliam/stats3/statafiles/rwm11.dta", clear (German Health Care Panel Data, Riphahn Wambach Million (2003), Greene (2007)) . reg newhsat female age handdum educ married working if year==1984 Source | SS df MS Number of obs = 3874 -------------+------------------------------ F( 6, 3867) = 141.19 Model | 4483.9589 6 747.326483 Prob > F = 0.0000 Residual | 20468.7796 3867 5.29319359 R-squared = 0.1797 -------------+------------------------------ Adj R-squared = 0.1784 Total | 24952.7385 3873 6.44274168 Root MSE = 2.3007 ------------------------------------------------------------------------------ newhsat | Coef. Std. Err. t P>|t| [95% Conf. Interval] -------------+---------------------------------------------------------------- female | -.186618 .0870046 -2.14 0.032 -.3571973 -.0160387 age | -.0388289 .0035637 -10.90 0.000 -.0458159 -.031842 handdum | -2.341489 .1236374 -18.94 0.000 -2.58389 -2.099088 educ | .1089876 .0173546 6.28 0.000 .0749626 .1430125 married | .2048268 .0918166 2.23 0.026 .0248133 .3848402 working | .2955985 .0912629 3.24 0.001 .1166704 .4745265 _cons | 7.409179 .2928951 25.30 0.000 6.834935 7.983422 ------------------------------------------------------------------------------ Sociology 63993Exam 1Page 2 . estat hettest Breusch-Pagan / Cook-Weisberg test for heteroskedasticity Ho: Constant variance Variables: fitted values of newhsat chi2(1) = 55.33 Prob > chi2 = 0.0000 . reg newhsat female age handdum educ married working if year==1984, robust Linear regression Number of obs = 3874 F( 6, 3867) = 129.51 Prob > F = 0.0000 R-squared...
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ex1_2012 - Sociology 63993Exam 1Page 1 Sociology 63993 Exam...

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