This paper points to some of the facts that have emerged from 20 years of research into the analysis of unit roots in panel data, an area that has been heavily influenced by two studies, IPS (Im, Pesaran, and Shin, 2003) and LLC (Levin et al., 2002). Some of these facts are known, others are...

This paper points to some of the common myths and facts that have emerged from 20 years of research into the analysis of unit roots in panel data. Some of these are wellknown, others are not. But they all have in common that if ignored the effects can be very serious. This is demonstrated using...

In this paper alternative approaches for testing the unit root hypothesis in panel data are considered. First, a robust version of the Dickey-Fuller t-statistic under contemporaneous correlated errors is suggested. Second, the GLS t-statistic is considered, which is based on the t-statistic of...

For univariate time series we suggest a new variant of efficient score tests against fractional alternatives. This test has three important merits. First, by means of simulations we observe that it is superior in terms of size and power in some situations of practical interest. Second, it is...

This paper proposes a new framework for studying the effects of monetary policy on business investment. Important ambiguities with the modeling of investment dynamics and interactions between real and financial decisions suggest modeling investment spending as a VAR. Based on a panel of...

To discuss generalized estimating equations as an extension of generalized linear models by commenting on the paper of Ziegler and Vens “Generalized Estimating Equations: Notes on the Choice of the Working Correlation Matrix”. Methods: Inviting an international group of experts to comment on...

In order to obtain exact distributional results without imposing restrictive parametric assumptions, various rank counterparts of the Dickey-Fuller statistic are considered. In particular, a rank counterpart of the score statistic is suggested which appears to have attractive theoretical...