NHTSA (National Highway Traffic Safety Administration) has undertaken several approaches to remedy the problem of missing blood alcohol test results in FARS (Fatality Analysis Reporting System). The approach currently in use employs a linear discriminant model that estimates the probability that a driver or nonoccupant has a BAC in grams per deciliter (g/dl) of 0.00, 0.01 to 0.09 or 0.10 and greater. The estimates are generated only for drivers and nonoccupants (pedestrians, pedalcyclists) for whom alcohol test results were not reported. The proposed methodology extends the current model by simulating specific values of BAC (blood alcohol concentration) across the full range of possible values rather than estimating probabilities. By imputing ten values of BAC for each missing value, valid statistical inferences like variance, confidence intervals and deviation tests can be drawn. The estimation of discrete values also facilitates analysis by non-standard boundaries of alcohol involvement (e.g., 0.08+). (A)
Abstract