Consider the model ya = 50 + 51% + 531:" + En E[a:,-,] i 0: 5&1:de : 0- Ail the observations are i.i.d. a) Can you estimate this model by the ESLS method using 2,- = (1, mi, tug, w? of instruments? Explain in detail. ) as a vector b) Write down the formula for the ESLS estimator clearly stating all the notations you USB. :2) Let Z denote the n x 4 matrix of instruments constructed for z,- above. Let C be an invertible 4 x 4 matrix of constants. Suppose that you want to use CZ; as the vector of instruments rather than 2i (the corresponding matrix of instruments is then Z 0' ) Show that the QSLS estimator based on the transformed vector of instruments 023,: coincides with the ZSLS estimator based on zi