This is vividly reflected by the dotted line, which is the fitted value from a regression of seasonally adjusted IUIC on a trend (T), an intercept dummy (D) with values of one prior to 1983 and zero afterward, and the product term (DxT), which captures the change in the slope parameter after 1983.
Table 1 summarizes the salient features of the seasonally unadjusted weekly IUIC.
Next, we examine the stochastic properties of the weekly IUIC.
Given the ambiguity regarding the stochastic nature of IUIC, the empirical work that follows will work with the variable in both log level and log first-differences.
Modeling the univariate properties of the IUIC requires identification of the models for the conditional mean and conditional variance.
Visual inspections, along with summary statistics reported earlier, suggest that the conditional mean of IUIC is potentially the outcome of four types of unobservable behavior consisting of seasonal ([y.