It can be conluded from this study that (1) empirical data from two sources confirm that driver safety belt effectiveness declines as car crash severities increases; (2) the probability that a driver is belted declines as crash severities increases - the drivers who would benefit most are those likely to buckle up (selective recruitement); (3) belt effectiveness estimates that ignore selective recruitenment are biased upwards by large amounts; (4) belts appear more effective at preventing fatalities than at preventing injuries; and (5) the results are consistent with a prior estimate, derived using a method unaffected by the biases discussed here, which found that, averaged over all crashes, safety belts reduce driver fatality risk by (42 plus or minus 4) percent. (A)
Samenvatting