1.1) An estimate is A) unbiased if its expected value equals the population value B) a number C) another word for estimator D) efficient if it has the smallest variance 1.2) Under imperfect multicollinearity A) the OLS estimator is biased even in large samples B) two or more of the regressors are highly correlated C) the OLS estimator cannot be computed D) the error terms are highly, but not perfectly correlated, across different observations.