Help-wanted advertising is used by businesses when they are caught short and need workers quickly, as might be expected to happen when business activity picks up after a downturn. Table 14.4.8 shows a Box€“Jenkins analysis of the help-wanted advertising index, while Figure 14.4.1 shows the data series with the Box€“Jenkins forecasts.20
a. What kind of process has been estimated?
b. Which estimated coefficients (if any) are significant?
c. Based on the figure, would you be surprised if the help-wanted advertising index dropped to 15 in the year 1995?
d. Based on the figure, would you be surprised if the help-wanted advertising index rose to 120 in the year 1996?
e. The forecasts in the figure appear to level off after about 1995. Does this tell you that the help-wanted advertising index will stop changing from year to year in the future? Explain.

FIGURE 14.4.1

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TABLE 14.4.8 Results of a Box Jenkins Analysis of the Help-Wanted Advertising Index Final Estimates of Parameters Type stimate AR 1 MA 1 Constant 50.653 5.302 Mean StDev t Ratio 0.5331 0.1780 2.99 -0.8394 0.1170 7.18 9.55 108.48 1136 No. of Obs.: 29 Residuals: SS 6161.77 (Backforecasts excluded) MS 236.99 DF 26 2001 100 0 1960 1970 0 190 2000 2010 Year