Consider a bivariate regression model with coefficient standard errors calculated using the usual formulae. Which of the following statements is/are correct regarding the standard error estimator for the slope coefficient?xi
(i) It varies positively with the square root of the residual variance (s) (ii) It varies positively with the spread of X about its mean value (iii) It varies positively with the spread of X about zero (iv) It varies positively with the sample size T
(a) (i) only
(b) (i) and (iv) only
(c) (i), (ii) and (iv) only
(d) (i), (ii), (iii) and (iv).
What result is proved by the GaussâMarkov theorem?xii (a) That OLS gives unbiased coefficient estimates (b) That OLS gives minimum variance coefficient estimates (c) That OLS gives minimum variance coefficient estimates only among the class of linear unbiased estimators (d) That OLS ensures that the errors are distributed normally.