Testing for stationarity in heterogeneous panel data in the presence of cross-section dependence

The panel variant of the KPSS tests developed by Hadri Hadri, K., 2000, Testing for stationarity in heterogeneous panels. Econometrics Journal, 3, 148–161] for the null of stationarity suffers from size distortions in the presence of cross-section dependence. However, applying the bootstrap methodology, we find that these tests are approximately correctly sized.