The Producer Price Index for finished consumer goods from 1980 through 2007 is in file XR18084, with 1982 5 100 and 1980 coded as t 5 1. Construct a firstorder autoregressive forecasting equation for these data, calculate the mean absolute deviation (MAD) for the fit of the forecast values to the actual values, then use the equation to forecast the PPI for 2008. Source: Bureau of the Census, Statistical Abstract of the United States 2009, p. 474.