The Defensive Driving Course, like other post-licensure driver training programs, is intended to reduce the rate of motor vehicle crashes among those who take the course. A review of the literature revealed 16 reports of studies of the effects of DDC. About a third of these studies provided methodologically strong tests of DDC, another third only weak, variously flawed tests, and the others were inadequate to test whether DDC had any effect. Only among the inadequate and weak tests were there large, positive effects of DDC. In the scientifically rigorous tests, DDC had no effect on crashes and decreased the frequency of traffic violations only slightly. The failure of violation reductions to be translated into crash reductions may indicate that the violation reduction is an artifact of traffic record procedures or that the changes in driver behavior, if real, were insufficient to modify individual crash likelihoods. In either event, the best scientific evidence indicates that DDC does not decrease the likelihood of motor vehicle crashes. (A) For related work see ITRD 287382.
Samenvatting