Campbell, John Y.; Shiller, Robert J. - Cowles Foundation for Research in Economics, Yale University - 1986
In a model where a variable Y is proportional to the present value, with constant discount rate, of expected future values of a variable y, the "spread" S - Y - qy will be stationary for some q whether or not y must be differenced to induce stationarity. Thus, Y and y are cointegrated. The model...