Can I make a brief comment on this debate. A residual based test for cointegration is base on the residuals from a cointegrating regression. Depending on whether the variables in the cointegrating regression have non zero drifts on should include a constants or a trend in the cointegration. If this is done properly there is no need to include a constant or a trend in the cointegrating regression. The ADF statistic may, however, depend to some extent on the inclusion of a constant or a trend in the original cointegrating regression. Can I recommend the account in Hayashi , F (2000), Econometrics, Princeton University Press.
John C Frain
Economics Department
Trinity College Dublin
Dublin 2
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John C Frain