TY - JOUR
T1 - A comparison of licensed driver counts from the Federal Highway Administration and driver licensing agencies in 11 states
AU - Evans, Alexander
AU - Benedetti, Marco H.
AU - Chang, Gregory
AU - Shoots-Reinhard, Brittany
AU - Chen, Zhenhua
AU - Smith, Gary A.
AU - Zhu, Motao
N1 - Publisher Copyright:
© 2023 Taylor & Francis Group, LLC.
PY - 2024
Y1 - 2024
N2 - Objective: Those who study motor vehicle crashes may rely on counts of licensed drivers to estimate crash, injury, or fatality rates. These counts may be obtained from the U.S. Department of Transportation Federal Highway Administration’s (FHWA) annual Highway Statistics Series or directly from state driver licensing agencies. However, previous studies have questioned the accuracy of these counts provided by the FHWA.Methods: To investigate this issue, we compared counts of licensed drivers from the FHWA and state licensing agencies in 11 states, categorized by sex and age group, from 2013 through 2017. We then assessed the impact of any potential differences by fitting two sets of Poisson regression models to estimate age- and sex-based driver fatality rate ratios. One set of models used counts from the FHWA as the offset and the other used counts from state licensing agencies.Results: Our analysis found that the differences between FHWA and state counts varied markedly. Seven states had substantial differences for at least one age group that spanned the entire study period. In several cases, these differences in license counts were large enough to produce directly contradictory driver fatality rate ratio estimates when comparing age groups.Conclusions: These findings highlight the continued concern regarding the accuracy of licensed driver counts from the FHWA and extend previous studies by illustrating the impact of using FHWA counts on statistical inference. We recommend against using these data for traffic safety research or policy evaluation. Nevertheless, we acknowledge the need for a centralized, easily accessible database for licensed driver data.
AB - Objective: Those who study motor vehicle crashes may rely on counts of licensed drivers to estimate crash, injury, or fatality rates. These counts may be obtained from the U.S. Department of Transportation Federal Highway Administration’s (FHWA) annual Highway Statistics Series or directly from state driver licensing agencies. However, previous studies have questioned the accuracy of these counts provided by the FHWA.Methods: To investigate this issue, we compared counts of licensed drivers from the FHWA and state licensing agencies in 11 states, categorized by sex and age group, from 2013 through 2017. We then assessed the impact of any potential differences by fitting two sets of Poisson regression models to estimate age- and sex-based driver fatality rate ratios. One set of models used counts from the FHWA as the offset and the other used counts from state licensing agencies.Results: Our analysis found that the differences between FHWA and state counts varied markedly. Seven states had substantial differences for at least one age group that spanned the entire study period. In several cases, these differences in license counts were large enough to produce directly contradictory driver fatality rate ratio estimates when comparing age groups.Conclusions: These findings highlight the continued concern regarding the accuracy of licensed driver counts from the FHWA and extend previous studies by illustrating the impact of using FHWA counts on statistical inference. We recommend against using these data for traffic safety research or policy evaluation. Nevertheless, we acknowledge the need for a centralized, easily accessible database for licensed driver data.
KW - Driver licensing
KW - driver fatality
KW - driving data quality
KW - exposure estimation
UR - http://www.scopus.com/inward/record.url?scp=85177454802&partnerID=8YFLogxK
U2 - 10.1080/15389588.2023.2278412
DO - 10.1080/15389588.2023.2278412
M3 - Article
C2 - 38165202
AN - SCOPUS:85177454802
SN - 1538-9588
VL - 25
SP - 133
EP - 137
JO - Traffic Injury Prevention
JF - Traffic Injury Prevention
IS - 2
ER -