1. A researcher is interested to know whether class attendance affects the outcome of a final exam among college students. The researcher obtains the following OLS estimates: Final 18 0.017 attendance + 3.23 priGPA (0.96) (0.034) (0.34) Sample size (n) = 680; R²= 0.134 (1) a. The researcher controls for the nonlinear effect of priGPA on final and obtains the following estimates: Final 32+ 0.008 attendance - 8.98 priGPA + 2.3 priGPA² (2) (2.9) (0.033) (2.29) n = 680; R2 = 0.169 (0.42) Is there evidence for increasing marginal returns to priGPA? In one or two sentences explain what the increasing marginal returns mean in this example. [8 marks]