In order to assess the validity of the specification of an econometric model, it is useful to have a variety of diagnostic statistics which might provide the evidence on the existence and possibly the type of misspecification involved. One source of diagnostics is hypothesis tests where the...

In spite of the importance of exogeneity in econometric modeling, an unambiguous definition does not seem to have been proposed to date. This lack has not only hindered systematic discussion, it has served to confuse the connections between "casuality" and "exogeneity". Moreover, many existing...