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Database Analysis 65
additional resources, but would fit well within NHTSA's crash data program. Adding the follow-
ing data fields is suggested:
· Right of way. This data element would identify which vehicle, if any, within a crash had the
right of way prior to the collision. This could be readily coded from the PAR in most cases.
Some state crash reports include right of way on the report. Right of way would be very use-
ful in most crashes in identifying the vehicle that primarily contributed to the crash.
· Accident type. The General Estimates System (GES) file and Crashworthiness Data System
(CDS) file both include an accident type variable coded at the vehicle level that captures the
relative position and movement of the vehicle prior to its first harmful event. The TIFA data
adds this to trucks in fatal crashes, but capturing this within the FARS system would be a valu-
able addition. An accident type field can identify key relationships that describe how the crash
occurred and suggest contribution (for example, by identifying the vehicle that crossed over
the center line in a head-on collision).
The following two fields would be useful although this would take additional resources and
possibly require some change in the management of the FARS file:
· Critical event is a field that would identify and describe the event that precipitated the vehicle
crash. This field is included in both the GES and CDS files, so the agency is very familiar with
(and, indeed, invented) its use.
· Critical reason captures the "reason" for the critical event, classified broadly as driver, vehicle,
or environment, with detailed levels under each. The variable is useful for identifying the
immediate failure that led to the crash and would shed considerable light on crash causation.
The field was used in the LTCCS, conducted jointly by the FMCSA and NHTSA, and in the
National Motor Vehicle Crash Causation Survey (NMVCCS), conducted by NHTSA. Thus,
the agency already has developed coding procedures for both variables.
However, adding these fields might require some changes to the FARS protocol. Both are dif-
ficult to code consistently and require a high level of focus and analysis. Currently, virtually all
FARS fields are coded by analysts located off-site, that is in the 50 states and District of Colum-
bia. But the coding of both GES and CDS is more centralized. In the LTCCS, both critical event
and critical reason were coded by a small number of analysts in two locations. The National Cen-
ter for Statistics and Analysis (NCSA) could adopt a similar method for the FARS file, if these
data elements were added.
4.3.8 Potential Measures to Improve Data Quality
The FARS quality control system is complete and mature. It is subject to annual review and
adjustment, including continuous training of the coders.
FARS might be improved if the system could be adapted to take advantage of the additional
information provided through the TIFA system. FARS has not engaged TIFA in this regard,
although one problem has been that information from TIFA has not been available in a timely
fashion. However, greater cooperation between the systems would be valuable for both.
4.3.9 Compatibility with Other Databases
The FARS file does not include case identifiers that can be used to uniquely link to other data
systems, such as the PAR number. Including the PAR number would provide a hard link. (Note
that the MCMIS Crash file report number field in the past was supposed to include the PAR
number in one of the fields, and it is recommended that MCMIS require that again. Currently,
many states use a random report number, rather than using the PAR number.)
