Inappropriate Detrending and Spurious Cointegration

The empirical literature is abundant with detrended cointegration, where cointegration relationships are tested and estimated with deterministic trend terms. Cointegration is, however, critically dependent on whether time series is detrended or not. A series of Monte Carlo experiments show that inappropriately detrended time series tend to exhibit a spurious cointegration. Although true time series are known not to be cointegrated, inappropriately detrended series tend to be cointegrated. Foreign exchange rates are analyzed to demonstrate the relevance and importance of the inappropriate detrending in the cointegration analysis.