Instrumental Variables (IV) methods identify internally valid causal effects for individuals whose treatment status is manipulable by the instrument at hand. Inference for other populations inevitably requires some sort of homogeneity assumption. I develop a simple theoretical framework that...

This paper analyzes conditions under which various k-class estimators are asymptotically normal in a simultaneous equations framework with many weak instruments. In particular, our paper extends the many instruments asymptotic normality results obtained by Morimune (1983), Bekker (1994), Angrist...

This paper proposes shrinkage methods in instrumental variable estimations to solve the ``many instruments'' problem. Even though using a large number of instruments reduces the asymptotic variances of the estimators, it has been observed both in theoretical works and in practice that in finite...

This paper considers models with time-varying individual effects (also known as factor models). The paper extends Ahn, Lee and Schmidt, Journal of Econometrics, 2001 and Bai, Econometrica, 2003 to allow a parametric function of time for the time factor. It provides a fixed-effects treatment of...

Researchers, policymakers, and parents are giving education reforms involving expanded school choice increased attention. Many view the heightened competition that would presumably result from such reforms as a panacea for the ills currently plaguing the public education system in the US....

We provide an argument for the limitation of Edgeworth expansions to many commonly used statistics in the weak instrument framework. However, we show that Edgeworth expansions hold for approximately similar tests regardless of the identification conditions. Finally, we consider simulation...

One important issue for the new Member States (NMS) of the EU is the choice of the exchange rate regime that will allow them to participate successfully in the EMU process. Two exchange rate arrangements, compatible with the EU Treaty and ERM2 regulations, deserve special attention: flexible...

In this paper it is shown that "classical" tests can become asymptotically inadmissible (i.e. we show that there exist uniformly better tests) if the information matrix becomes stochastic: A typical example is the augmented Dickey-Fuller test for unit roots (in case of no deterministic trend. We...

State governments finance their expenditures with multiple tax instruments, so when collections from one source decline, they are typically compensated by greater revenues from other sources. This paper addresses the important question of the extent to which personal and corporate income taxes...