Answer Happy

2. True or False? Explain briefly. Each of the following question is worth 3 marks. (a) We should always test for autocorrelation when using cross-section data because if it is present the OLS estimator is biased.
(b) In the following ‘True or False questions, we consider the classical assumptions for OLS, except for the variance-covariance matrix 1 of the disturbance term. If 2 0 0 -- 02 Ω = σ2 ... 0 0 2 0 GLS is more efficient than OLS. (c) If 0 0 ... 0 Ω: : - = a2 0 : 0 ... 0 OLS is BLUE. (d) If Ω = σ2 1 0 0 1 0 1 1 0 0 1 1 0 1 0 0 1 OLS is BLUE.