What is Heteroskedasticity Recall the assumption of homoskedastic implied that conditional on the explanator variables the variance of the unobserved error u was constant If this is not true that is if the variance of u is different for different values of thex's. then the errors are heteroskedastic
Introduction [Again, by and large, I will follow OR, Chap. 8, so I will keep these notes to a minimum. Review of key definitions Recall our three payoff aggregation criteria: discounting, i.e (u2)≥1>(2 (also recall that the payoff profile corresponding to a stream (ut)is taken to be(1 8)2t18t-u(a)); limit of means