EVALUATION OF THE RANDOM BREATH TESTING INITIATIVE IN VICTORIA 1989- 1991: MULTIVARIATE TIME SERIES APPROACH

A quasi-experimental time series evaluation of the effect of a random breath testing (RBT) initiative, introduced late in 1989 in Victoria, on crashes during 1990 was undertaken. This report presents an evaluation which uses another method of estimating the effect of the initiative. The RBT initiative involved a different method of enforcement compared with past operations, with bus-based RBT stations replacing car-based stations and a publicity campaign through all mass media. Multivariate time series modelling of high alcohol hour serious casualty and fatal crashes was undertaken to estimate the change relating to the RBT initiative during 1990 and 1991. A form of time series modelling known as ARIMA Intervention Analysis was used to estimate effects during 1990, whilst a multiple regression approach was used to estimate effects during 1991. The findings of the present study indicate that the initiative resulted in an 18% reduction in high alcohol hour serious casualty crashes and a 24% reduction in high alcohol hour fatal crashes in Melbourne in 1990, but no statistically significant effect during 1991. In rural Victoria, high alcohol hour casualty crashes decreased by 13% in 1990 and by 24% in 1991, whilst there were no statistically significant effects in high alcohol hour fatal crashes in rural Victoria in 1990 or 1991. (a)