I'm fitting a regression model $y_t$ to a time series $x_t$ (not a dynamic model involving ARMA terms!). I saw that useful predictors to put in my model are $t$, seasonality variables and lagged values of other time-series that are affecting my time-series.
question: why don't they mention the time series lagged variables themselves $x_{t-1}$, $x_{t-2}$? this is different than a dynamic regression model that uses $y_{t-1}$ or $\epsilon_{t-1}$, but sounds so simple and useful...