At the end of 1970, the state of Victoria introduced a law making compulsory the wearing of seat belts (largely lap-sash combinations) where fitted in motor vehicles, and for the next 9 months it was the only state with such a law. The effect of the legislation is evaluated by a before-and-after comparison, the frequency of deaths and of non-fatal casualties in the other states and among other road users being used as controls. The concurrent effects of an economic recession and a newspaper safety campaign are examined. It is concluded that, after allowing for concurrent factors, the legislation caused a statistically significant reduction of 21 per cent in vehicle occupant deaths in the metropolitan area of Victoria and 10 per cent (non-significant) in the non-metropolitan. For non-fatal injuries the corresponding reductions (both significant) were 13 and 11 per cent. Fluctuations in the economy have a distinct effect on the frequency of road casualties, but the effect of the newspaper campaign and concurrent factors appeared to be insignificant. The Appendix outlines the method used for analysing complex contingency tables.
Samenvatting