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Using FARS data to Classify Unspecified MV-traffic Deaths by Person Type in NVSS data. J. Lee Annest, Ph.D. Director, Office of Statistics and Programming National Center for Injury Prevention and Control. The Question. How many MV-traffic deaths are occupants in the vehicle?.
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Using FARS data to Classify Unspecified MV-traffic Deaths by Person Type in NVSS data J. Lee Annest, Ph.D. Director, Office of Statistics and Programming National Center for Injury Prevention and Control
The Question How many MV-traffic deaths are occupants in the vehicle?
The Problem • In 2001, almost 35% of 42,443 MV-traffic deaths in the NVSS were unspecified for person type (occupant, motorcyclist, pedal cyclist, pedestrian, other) • Current death certificate used in most states not set up to routinely capture person type • New death certificate has a separate data item that should help classify MV traffic deaths by person type (needs to be assessed)
One Possible Solution • Use data from the Fatal Analysis Reporting System (FARS) to allocate unspecified MV-traffic deaths into specified person type categories (occupant, motorcyclist, pedal cyclist, pedestrian, other)
Method • Use the known distribution of FARS deaths for specified person type to determine where to allocate the unspecified MV-traffic deaths in the NVSS.
Allocation Process • First, allocate unspecified deaths into specified person type categories other than occupant • Then, put the remaining unspecified MV-traffic deaths into occupant.
Allocation Rules Applied • Distribute MV-traffic deaths into person type categories within specific age-by-sex groupings • Allocate unspecified deaths into person type categories other than occupant as follows: > If the number of specified death is higher in FARS than NVSS, then change NVSS to the higher number > If the number of specified deaths is higher in NVSS than FARS, then do not change NVSS
Example Pedal cyclist (Males 15-19 years) Deaths Data Source Observed Allocated FARS 66 -- NVSS 57 66 ---------------------------------------------------- Redistributed unspecified = 9
Example Pedestrian (Females 1-4 years) Deaths Data Source Observed Allocated FARS 35-- NVSS 56 56 ---------------------------------------------------- Redistributed unspecified = 0
Allocation Rules Applied 3. Allocate the remaining unspecified deaths to the occupant category 4. Sum deaths across age-by-sex groupings to get final numbers: overall and by broader age and sex groups. 5. After allocation, the distributions of MV-traffic deaths by person type should be very similar for FARS and NVSS
Conclusions • Allocation procedure works well for obtaining national estimates • Procedure not tested for state and local estimates; need to consider: > FARS deaths – reported by where the fatal crash occurred >NVSS deaths – often reported by place of residence rather than place of occurrence