Economics 120B Fall 2007 Dr. ColGPA = 1.

Economics 120B Fall 2007 Dr. ColGPA = 1.392 Where colGPA is measured on a four-point scale, hsperc is the percentile in the high school graduating class (defined so that, for example, hsperc = 5 means the TOP five percent of the class), and sat is the combined math and verbal scores on the student achievement test. A. Why does it make sense for the coefficient on hsperc to be negative? What is the predicted college GPA when hsperc = 20 and sat =1050? Suppose that two high school graduates, A and B, graduated in the same percentile from high school, but student As SAT score was 140 points higher (about one standard deviation in the sample). What is the predicted difference in college GPA for these two students? Holding hsperc fixed, what difference in SAT scores leads to a predicted colGPA difference of 0.50, or one-half of a grade point? Comment on your answer. Construct a 95% confidence interval for the effect of hsperc on college GPA. Can you reject the null hypothesis that