Trends revisited o A trending series cannot be stationary, since the mean is changing over time o A trending series can be weakly dependent o If a series is weakly dependent and is stationary about its trend, we will call it a trend-stationary process o As long as a trend is included, all is well Economics 20- Prof anderson 6Economics 20 - Prof. Anderson 6 Trends Revisited A trending series cannot be stationary, since the mean is changing over time A trending series can be weakly dependent If a series is weakly dependent and is stationary about its trend, we will call it a trend-stationary process As long as a trend is included, all is well