For Exercises 13.18 to 13.20, see pages 670–671; for 13.21 to 13.23, see page 677; for 13.24, see page 679.

Question 13.24

13.24 Chinese car ownership.

In Example 13.14 (pages 669–670), an exponential trend-only model was fitted to the yearly time series of the number of passenger cars owned in China. In Exercise 13.23 (page 677), you were asked to determine the fitted model for the number of passenger cars in logged units.

  1. Calculate the predicted number of passenger cars in logged units for each year in the time series.

  2. Calculate the residuals using the fitted values from part (a). That is, calculate

    for each year in the time series.

  3. Make a time plot of the residuals. Is there visual evidence of autocorrelation in this plot? If so, describe the evidence.
  4. Compute the correlation between successive residuals and and test the hypothesis of zero correlation. Is there evidence of autocorrelation? Explain.

china