= Let Yi (Y1,..., YiT)" and {Y} be an i.i.d. sample. Further suppose that Yit = A + B + Vit with E [Vit] =0 and where we treat A, and Bt as parameters to be estimated. Let D; be as in (4.36) and consider estimating (A,..., An) and (B,..., BT) by T T (a {A}") = mx_ arg min aER", {b}ERT n Yi-Da-1{t = t}bt i=1 t=1 f=1 (a) Derive a closed form expression for , by using Theorem 2.2.1. (b) Writing an = (A1,..., n)', show that for any j, ; is not consistent for Aj.