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Page 108
Suggested Citation:"Appendix B Descriptive statistics." National Academies of Sciences, Engineering, and Medicine. 2019. Identification of Factors Contributing to the Decline of Traffic Fatalities in the United States from 2008 to 2012. Washington, DC: The National Academies Press. doi: 10.17226/25590.
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Page 108
Page 109
Suggested Citation:"Appendix B Descriptive statistics." National Academies of Sciences, Engineering, and Medicine. 2019. Identification of Factors Contributing to the Decline of Traffic Fatalities in the United States from 2008 to 2012. Washington, DC: The National Academies Press. doi: 10.17226/25590.
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Page 109

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Page 93 Appendix B Descriptive statistics Table B-1 Variables in MCS and MNCS Models Variable  Units  Non‐missing  observations  Mean  Median  Std Dev  Range  10th Pctl  90th Pctl  TotalVMT  Millions of miles  600  58,855.4  46,758.5  59,853.4  324,674.0  8,994.0  110,541.0  UrbanVMT  Millions of miles  600  38,189.8  25,532.5  47,024.8  266,918.0  2,643.5  75,298.0  RuralVMT  Millions of miles  600  20,665.6  17,419.0  15,586.2  85,131.0  4,033.5  38,043.0  ruralvmt_prop  Proportion  600  0.44  0.44  0.19  0.91  0.19  0.72  cap_m_lag  1000s dollars per  highway mile (2013  dollars)  550  64.2  49.4  47.7  270.9  19.9  123.6  safe_total_m_lag  1000s dollars per  highway mile (2013  dollars)  550  10.8  8.2  10.0  58.1  2.5  23.5  gdp_cap  Constant 2013 dollars  600  57,200.7  56,367.8  11,595.9  83,060.0  43,268.3  72,262.3  MedIncome  Constant 2013 dollars  600  54,591.7  53,886.7  8,276.6  37,527.7  44,246.8  67,301.0  UnEmp_16_24  Percent  600  12.8  12.1  3.8  19.2  8.5  18.5  pump_price  Constant 2013 dollars  600  2.81  2.84  0.6  2.88  1.95  3.68  Beer  Gallons per capita  600  1.2  1.2  0.2  1.2  1.0  1.5  Wine  Gallons per capita  600  0.4  0.3  0.2  0.9  0.2  0.6  BeltUse  Percent  590  81.3  81.9  9.3  48.4  68.6  93.3  DUI_rating  Index  600  19.3  19  3.3  17  15  24  Belt_rating  Index  600  2.2  2  1.1  4  1  4  MC_hlmt_rating  Index  600  2.7  2  1.2  4  2  4  post1991  Percent  600  93.4  95.3  4.7  15.4  86.9  97.6 

Page 94 Table B-2 Variables in Change Model Variable  Non‐missing  observations  Mean  Median  Std Dev  Range  10th Pctl  90th Pctl  TotalVMT_chng  550  0.00622  0.00789  0.02562  0.35682  ‐0.02135  0.03286  Ruralvmt_prop_chng  550 ‐0.01939  ‐0.00265  0.07630  0.89543  ‐0.05241  0.01552  pump_price_chng  550  0.05467  0.09493  0.12895  0.56582  ‐0.10027  0.17155  gdp_cap_chng  550 ‐0.01966  ‐0.01713  0.06465  1.40280  ‐0.05227  0.01856  MedIncome_chng  550 ‐0.00553  ‐0.00444  0.02945  0.21803  ‐0.04311  0.02765  UnEmp_16_24_chng  550  0.03487  0.02442  0.19197  1.58067  ‐0.18368  0.30060  cap_m_chng_lag  500  0.00980  0.00442  0.19744  1.88702  ‐0.21202  0.23149  safe_total_m_chng_lag  500  0.02805  0.03784  0.31743  3.83360  ‐0.21989  0.29174  BeltUse_chng  537  0.01669  0.01056  0.04165  0.49134  ‐0.02260  0.06047  DUI_rating_chng  550  0.01356  0.00000  0.04602  0.47000  0.00000  0.05268  MC_hlmt_rating_chng  550  0.00000  0.00000  0.04184  1.38629  0.00000  0.00000  Beer_chng  550 ‐0.00591  ‐0.00755  0.03412  0.36229  ‐0.04078  0.02765  Wine_chng  550  0.02910  0.02740  0.05024  0.40705  ‐0.00552  0.08004  Post1991_chng  550  0.01556  0.01049  0.01463  0.04889  0.00308  0.02979 

Next: Appendix C State-specific parameters for the MCS model »
Identification of Factors Contributing to the Decline of Traffic Fatalities in the United States from 2008 to 2012 Get This Book
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Between 2005 and 2011, the number of traffic fatalities in the U.S. declined by 11,031, from 43,510 in 2005 to 32,479 in 2011. This decline amounted to a reduction in traffic-related deaths of 25.4 percent, by far the greatest decline over a comparable period in the last 30 years.

Historically, significant drops in traffic fatalities over a short period of time have coincided with economic recessions. Longer recessions have coincided with deeper declines in the number of traffic fatalities. This report from the National Cooperative Highway Research Program, NCHRP Research Report 928: Identification of Factors Contributing to the Decline of Traffic Fatalities in the United States from 2008 to 2012, provides an analysis that identifies the specific factors in the economic decline that affected fatal crash risk, while taking into account the long-term factors that determine the level of traffic safety.

A key insight into the analysis of the factors that produced the sharp drop in traffic fatalities was that the young contributed disproportionately to the drop-off in traffic fatalities. Of the reduction in traffic fatalities from 2007 to 2011, people 25-years-old and younger accounted for nearly 48 percent of the drop, though they were only about 28 percent of total traffic fatalities prior to the decline. Traffic deaths among people 25-years-old and younger dropped substantially more than other groups. Young drivers are known to be a high-risk group and can be readily identified in the crash data. Other high-risk groups also likely contributed to the decline but they cannot be identified as well as age can.

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