For the general Gauss-Markov model with E(Y)=X[beta] and Var(Y)=V, we give a concise proof of an explicit characterization of the general nonnegative-definite covariance structure V such that the best linear unbiased estimator, weighted least-squares estimator, and least-squares estimator of...

The livestock industry uses information on meat prices at different stages in the marketing system to make production decisions. When grocery stores began using electronic scanners to capture prices paid for meat, it was assumed that the livestock industry could capitalize on having these...