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Unformatted text preview: Sociology 63993—Exam 2—Page 1 S o c i o l o g y 6 3 9 9 3 E x a m 2 A n s w e r K e y [ D r a f t ] M a r c h 2 6 , 2 0 1 0 I. True-False. (20 points) Indicate whether the following statements are true or false. If false, briefly explain why. 1. A researcher has included extraneous variables in her model. Increasing her sample size will help with the problems that are created by doing this. True. Extraneous variables lead to larger standard errors. Increasing sample size will help to reduce the standard errors. 2. A researcher obtains the following: . estat ovtest Ramsey RESET test using powers of the fitted values of warm Ho: model has no omitted variables F(3, 2288) = 3.81 Prob > F = 0.0098 This suggests that she should add interaction terms to her model. False. She should add powers of X, e.g. X^2, X^3, X^4. 3. A researcher regresses income on the respondent’s race, years of education, IQ, and father’s education (i.e. the number of years of education the respondent’s father had). The estimated effect of father’s education is 0 and is statistically insignificant. This means that, in terms of their own income, respondents gain no benefit from having a better educated father. False (or at least not necessarily true). Father’s education may have an indirect effect on child’s income, e.g. having a better educated father may lead to a better educated child which in turn leads to a higher income. This is a slight variation of the status attainment example we went over in the logic of causal order. 4. In order to make interaction effects more interpretable, the dependent variable should be centered about its mean. False. You should center the continuous independent variables. Centering the dependent variable will only cause the intercept to shift. 5. A researcher hypothesizes that informedness (measured on a 100 point scale) positively affects feelings of political efficacy for whites but has a negative effect for blacks. She obtains the following: β White = 0 β Inf = 7 β Inf*White = -5 β Inf and β Inf*White are both highly significant. The results support the researcher’s hypothesis. Sociology 63993—Exam 2—Page 2 False. For both whites and blacks, the effect of informedness is positive (7 for blacks and 7 – 5 = 2 for whites). To add insult to injury, the effect is actually more positive for blacks than it is for whites. II. Path Analysis/Model specification (25 pts). A sociologist believes that the following model describes the relationship between X1, X2, X3, and X4. All her variables are in standardized form. The estimated value of each path in her model is included in the diagram. a. (5 pts) Write out the structural equation for each endogenous variable, using both the names for the paths (e.g. β 42 ) and the estimated value of the path coefficient....
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- Spring '11
- Sociology, researcher, Tea Party protests, social conservatism