Table 1: Analysis of deviance table for number of traffic accidents. Poisson model with log-link function. Traffic intensity is included as background, and effect of year is modeled by using natural splines with 𝑑 𝑓 = 4 .

𝑑 𝑓 EstimateDevianceResidual 𝑑 𝑓 Residual Deviance 𝑃 ( > | 𝜒 | )

Season1 0 . 1 2 29.711025103.90 < .0001
DST1 0 . 1 7 19.991015083.92.8212
Year4 0 . 2 6 1086.72973997.20 < .0001
Road traffic total1 0 . 0 1 26.64963960.56 < .0001

Interactions
Season: DST10.0526.70953933.86 < .0001
DST: Year40.27152.13913781.73 < .0001
Season: Year40.05457.86873323.87 < .0001