=+a) What components can you see in this plot?

Here’s an AR(14) model fit to these data.

Dependent variable is: Gas Price 130 total cases of which 14 are missing R squared = 31.0% R squared (adjusted) = 30.4%

s = 0.1587 with 116 - 2 = 114 degrees of freedom Variable Coefficient SE(Coeff) t-ratio P-value Intercept 5.34842 0.2354 22.7 6 0.0001 Lag14 -0.463680 0.0647 -7.16 60.0001 Here’s a time series plot of the model.

3.25 3.50 3.75 4.00 30 60 90 120 Gas Price ($)

Weeks M19_SHAR8696_03_SE_C19.indd 712 14/07/14 7:37 AM Exercises 713