title: Examination of some possible biases in double pair comparison estimates of safety belt effectiveness.
abstract: Biases in double pair comparison estimates of safety belt effectiveness due to two effects (noncoding of some surviving passengers, and driver/passenger impact during crashes) are investigated by calculating effectiveness from fatality frequencies assumed altered by the biases. Noncoding surviving right-front passengers does not affect estimates for drivers, but does overestimate slightly passenger effectiveness. Two biasing driver/passenger contact effects occur for right-side impacts--a "cushioning" effect (risk to unbelted driver is reduced by striking passenger rather than the vehicle interior) and a "missile" effect (passenger risk is increased by being struck by unrestrained driver). Cushioning and missile effects both reduce estimates; their combined effects could cause right-side impact effectiveness to be underestimated by as much as 20% (probably much less). Correcting for all effects increases the overall estimate from 42.6% to 43.2%. Thus, to the nearest percent, the result is still that if all presently unbelted drivers and right-front-seat passengers were to become wearers, fatalities to this group would decline by (43 +/- 3)%.
authors: Operating Sciences Department, General Motors Research Laboratories, Warren, MI 48090.
authors: L
authors: L
authors: Evans
mesh_terms: D000063:Accidents, Traffic; D005069:Evaluation Studies as Topic; D006801:Humans; D008962:Models, Theoretical; D012622:Seat Belts