Gregory-Hansen Cointegration Test with Regime Shift

The Gregory-Hansen test, introduced by Allan Gregory and Bruce Hansen in 1996, extends the standard Engle-Granger cointegration framework to allow for a single unknown structural break in the cointegrating relationship. It is designed for researchers who suspect that the long-run equilibrium between integrated variables may have shifted at some point during the sample period, and who wish to test for cointegration without presupposing the break date.