Data Linkage to Other Data Sources to Minimize Data Collection
This guideline is recommending linkage of the crash data file to other sources of
information related to the environment of crash or to the vehicles and people involved in
the crash. By collecting the elements which permit linkage to these other data files, the
crash data are enhanced without overburdening data collection. The files to be linked
are:
- Roadway
- Driver
- Vehicle
- Medical Outcome
- EMS
- Emergency Department
- Hospital Discharge
Crash data alone do not indicate the magnitude of the problem of motor vehicle crashes
or the significance of highway safety countermeasures. They do not provide details about
the roadway, vehicle, the history of the driver, or the medical and financial consequences
for those who are injured. Collection of this information in the crash data are beyond the
scope of the police function and would represent a duplication of effort because the data
are collected elsewhere.
Roadway inventory, driver licensing, vehicle registration, EMS, emergency department,
hospital, death certificate, census and other state data contain information related to
motor vehicle crashes. Some of the data, such as the driver licensing, vehicle
registration, and roadway inventory files are collected routinely rather than at the time of
the crash. Other data, such as the crash and injury records are collected at the time of
the crash at the scene, en route, at the emergency department, in the hospital, and after
hospital discharge. Together these various data sources provide information about the
environment surrounding the crash event, the circumstances of the crash, and the medical
and financial consequences for those persons who are injured. When these files are
linked, as indicated in the diagram below, it is possible to describe in detail the
components of a crash and the events at the scene and to follow the persons injured in
the crash from the scene through the health care system. Linked data make it possible to
determine who is at risk, at what cost and the factors that make a difference to injury
outcome. (See Appendix G)
Example of a Data Linkage System
An example of data linkage is the Crash Outcome Data Evaluation System project which
evolved from the Intermodal Surface Transportation Efficiency Act of 1991 (ISTEA).
ISTEA mandated that the National Traffic Safety Administration (NHTSA) prepare a
Report to Congress about the benefits of safety belt and motorcycle helmet use. To
obtain the crash and injury outcome information needed for this report, NHTSA sponsored
the CODES project, awarding grants to Hawaii, Maine, Missouri, New York, Pennsylvania,
Utah, and Wisconsin. Each grantee linked the available state crash, EMS, emergency
department, hospital discharge, insurance, and other traffic records and performed
uniform analyses of the effectiveness of safety belts and motorcycle helmets. The Report
was delivered to Congress in February, 1996.
Benefits of Linkage
Data linkage expands the usefulness of each data file being linked without the delay and
expense of new data collection. Linkage makes it possible to evaluate the relationship of
specific roadway, crash, vehicle, and human factors at the time of a motor vehicle crash.
It also permits these specific factors to be linked to health outcome data to determine their
medical and financial consequences. Understanding what increases injury severity and
health care costs facilitates choosing safety priorities that have the most impact on
reducing death and disability. This information is particularly useful for decision making
by safety program managers, engineers and state legislators. At the same time, the
linkage process itself improves the quality of state data and promotes collaboration
between the traffic safety, highway safety and injury control communities.
Please send any comments to:
muccmail@nhtsa.dot.gov
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