Using the data MEAP00 01 to answer the following: (a) [ 5 points] Estimate the model math4 = β0+ β1lunch + β2log (enroll) + β3log (exppp) + u by OLS and obtain the usual standard errors and the fully robust standard errors. How do they generally compare? (b) [ 10 points] Apply the special case of the White test for heteroscedasticity. What is the value of the F test? What do you conclude? (c) [ 10 points] Obtain ˆ gias the fitted values from the regression log (ˆ u2 i) on ? math4i and ? math4i 2, where ? math4i are the OLS fitted values and the ˆ ui are the OLS residuals from the regression in part (a). Letˆhi = exp (ˆ gi) . Useˆhi to obtain the WLS estimates of the parameters in the model from part (a). Are there big differences between the WLS and OLS estimates? (d) [ 5 points] Obtain the standard errors for WLS that allow misspecification of the variance function. Do these differ much from the usual WLS standard errors?