We want to estimate the following simple linear regression model with heteroskedas- ticity by Generalized Least Squares (GLS): i = 1,..., n Yi Bo + Bixi + Ui = where Var(u|x) = (3+5x2)o and o is a population parameter. (2) Explain how the GLS estimators are obtained for this specific model. Describe the underlying intuition of the GLS estimation procedure. Provide mathematical formulas where appropriate. (8 marks) We want to estimate the following linear regression model by OLS: y = Bo + Bx + Bx2 + 3x3 + u We are concerned about the potential problem of heteroskedasticity in the regres- sion error. How would you test for the presence of heteroskedasticity using the original White Test? State carefully the null hypothesis of the test and write down any regres- sion equation you would need to estimate. (7 marks)