# Errata for R 2nd Edition SECOND Print

**Page/Section**

p. 149, second para

**Correction**

Should be:

The forecasted residual for April 2001 is computed by plugging in the most recent **mean-centered** residual from March 2001 (equal to 12.108 **- 0.3728**) into the AR(1) model: 0.3728 + (0.5998)(12.108 **- 0.3728**) =** 7.411**. The positive value tells us that the regression model will produce a ridership forecast for April 2001 that is too low and that we should adjust it up by adding **7,411** riders... the improved two-stage model [regression + AR(1) correction] corrected it by increasing it to** 2,011,682** riders.