1. The author of one of the readings makes the point that laboratory experiments of racial attitudes suffer from limited generalizability. (The phrased used was "Has low external validity"). What does the author mean? 2. A study collected data from a random sample of 600 UWT students to examine the relationship between hours spent studying and GPA. The following relationship was found, with GPA expressed on a 4.0 scale, and hours/week spent studying. GPA = 2.0 + .1 x hours spent studying SE: (.04) a. Explain with as much precision as you can the relationship found between hours/wk studied and predicted GPA. For instance, what predicted difference would it make if one studied 15 hours instead of 10 hours/week? b. Why might the study above suffer from omitted variable bias? Be clear in explaining the potential source of the bias, and its direction (overestimate? Underestimate?) 3. A study examined the factors explaining differences in the test scores of applicants trying to get into the Army, based on the applicant's high school GPA, race (where African American candidates are coded as "1" and others are coded as "0"), and a measure of the quality of the applicants' high school, measured on a scale of 1-10. Two versions of the equation were estimated with the following results: (1) Test score = 100 + 50 x high school GPA - 110 x race SE: (5) (15) R^2=0.25 (2) Test score = 50 + 45 x high school GPA - 5 x race + 50 x high school quality SE: (3) (20) (15) R^2=0.40 Can you explain what the results tell you? What is equation (1) an example of?