An Extension of the Induced Exposure Method of Estimating Driver Risk

SUMMARY An important problem in road safety is to estimate the rate of involvement of drivers in accidents per unit of exposure, or road usage. Typically, good data on numbers of drivers involved are available for the numerator of this ratio, but data on road usage for the denominator are often not available. To circumvent this difficulty, techniques of induced exposure were developed in the 1960s, to derive estimates of rates of driver involvement solely from data on numbers of drivers. None of the existing variants of the induced exposure technique seems entirely satisfactory, however. This paper derives a new version of the induced exposure approach and illustrates its application to accident data for Scotland over the period 1986-90.