is the vector of coefficient s, \alpha_{i} are the random effects, and u_{it} is the error term, then \alpha_{i} should have a normal distribution with mean zero and a constant variance. The coefficients can be estimated via \widehat{\beta}=(X'\Omega^{-1} X)^{-1}(X'\Omega^{-1}Y),\, \widehat{\Omega}=\Iota \otimes \Sigma,\, where X and Y are the matrix version of