Some Discrete Approximations to Continuous Time Stochastic Models

Abstract

Summary The paper considers the asymptotic biases in various econometric estimators when data generated by a stochastic differential equation system of the form d y d t − A y ( t ) = B z ( t ) + a ( t ) are estimated by approximating these equations in the form { y ( t + δ ) − y ( t ) } / δ = 1 2 A { y ( t + δ ) + y ( t ) } + 1 2 B { z ( t + δ ) + z ( t ) } + v ( t ) , where y(t) is a vector of endogenous variables, z(t) is a vector of exogenous variables and A and B are matrices of fixed coefficients, assumed estimated subject to certain a priori restrictions. It is shown that the asymptotic biases are O(δ2) as δ→0, on reasonable assumptions.