Question

A researcher was interested in how students’ Graduate Record Examinations scores (GREQ- Quantitative and GREV-Verbal) predict college students’ graduate school Grade Point Average (GGPA). He collects data from 30 college students. The GRE Quantitative (X1) and GRE Verbal (X2) scores can range from 400-1600 (Note. This is the old GRE score scale). GGPA (Y) can range from 0.00 to 4.00.

f. What proportion of variance in graduate grade point average cannot be accounted by the variability in the quantitative GRE and verbal GRE scores in combination? In other words, what is the unexplained variation in the regression model. (6 p)

g. Is this proportion of variance statistically significant at the .05 level of significance? Justify your answer. This includes providing the parameter being estimated, the statistical test (F, t, etc.) and its value, degrees of freedom associated with the statistical test. (14 p)

h. Using an alpha level of .05, justify your decision as to whether the regression coefficients for GREQ and GREV (when evaluated separately or after controlling for the other) are statistically significant. Justifying your decision includes providing the parameter(s) being estimated, the statistical test (s) (t, F etc.) and its (their) value, degree(s) of freedom associated with the statistical test(s). (14 p)

i. If someone were to increase their GRE-Quantitative score by 50 points, how much would you expect his or her GPA to change, after controlling for the GRE-Verbal variability? Show how you calculated your answer. (8 p)

j. In your own words explain why you think that the model did not explain all of the variability in GGPA. In other words, what other factors might play a role in increasing the amount of variability explained in GGPA. (8 p)

Answer 1