Collisions with injuries Quebec City^{*} | Collisions with material damages^{†} | Collisions with injuries for the rest of the province^{*} | ||||

β | p Value | β | p Value | β | p Value | |

AR_{1} | – | – | 0.47 | 0.01 | – | – |

SAR_{1} | – | – | −0.22 | 0.03 | – | – |

SAR_{2} | – | – | −0.44 | 0.01 | – | – |

SAR_{3} | – | – | −0.69 | 0.01 | – | – |

SMA_{1} | 0.55 | 0.01 | – | – | 0.32 | 0.01 |

Intervention | 8.75 | 0.02 | −63.58 | 0.05 | 41.11 | 0.48 |

Trend | – | – | 1.12 | 0.01 | – | – |

Constant | – | – | 825.83 | 0.01 | – | – |

Model parameters | ||||||

(p,d,q) s(p,d,q)_{12} | (0,0,0) (0,1,1) | (1,0,0) (3,0,0) | (0,0,0) (0,1,1) | |||

Test for autocorrelation | ||||||

Q^{‡} | 0.44 (lag 1), p>0.51 | 0.03 (lag 1), p>0.86 | 1.95 (lag 1), p>0.16 | |||

Q^{‡} | 13.75 (lag 12), p>0.32 | 10.29 (lag 12), p>0.59 | 10.96 (lag 12) p>0.53 |

The interaction term (time×intervention) was not statistically significant and therefore pulled out of the three models.

↵* Autoregressive and moving-average parameters were significant in the estimation stage but were no longer significant when the independent variables were included in the models. They were therefore discarded from the final models.

↵† When a linear trend was included in the model, 11 dummy variables for each month were added in the model to control for seasonal variations in the distribution of collisions (December=reference category).

↵‡ Box–Ljung test for autocorrelated residuals.