In this paper we suggest panel data unit root tests which allow for a structural breaks in the individual effects or linear trends of panel data models. This is done under the assumption that the disturbance terms of the panel are heterogenous and serially correlated. The limiting distributions of the suggested test statistics are derived under the assumption that the time-dimension of the pane...

We investigate the performance of some homogenous first and second generation panel unit root tests under alternative forms of cross sectional dependence. We formalize contemporaneous correlation through factor models, spatial autoregressive error models and combinations thereof. Our findings confirm that while the first generation test of Levin, Lin, and Chu (2002) suffers from substantial siz...

Although the impacts of structural instability on testing for unit root have been studied extensively for univariate time series, such impacts on panel data unit root tests are still relatively unknown. A major issue is the choice of model in accommodating different types of break (instability) prior to testing for unit root. Specifically, researchers must specify a potential break in the inter...

The base currency effect in the purchasing power parity (PPP) literature refers to the stylized fact that tests on German mark real exchange rates are more likely to support mean reversion than analogous tests on US dollar rates. Using a panel of 19 OECD currencies, 1973-1997, we employ different panel unit root approaches to investigate the view that this effect can be attributed to neglected ...

e d In the Box-Jenkins approach to analyzing time series, a key question is whether to difference th ata, i.e., to replace the raw data {y } by the differenced series {y −y }. Experience indicates that m t t t −1 ost economic time series tend to wander and are not stationary, but that differencing often yields a e r stationary result. A key example, which often provides a fairly good descriptio...