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Improving Motor Carrier Safety Measurement (2017) / Chapter Skim
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Appendix C: Item Response Theory Example Using Motor Carrier Management Information System Data - Jacob Spertus
Pages 145-150

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From page 145...
... A full implementation would look roughly similar, but with many more carriers and violations included. This appendix is included to show that the proposed model is relatively easy to implement in the Motor Carrier Management Information System.
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From page 146...
... The carrier subpopulation are those carriers with 100 or more average power units (APUs) , more than 80,000 VMT per APU reported, and less than 200,000 VMT per APU reported (medium to high utilization carriers according to SMS methodology)
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From page 147...
... 1.0 Probability of receiving given violation 0.8 0.6 0.4 0.2 0.0 −5 0 5 10 Underlying Carrier Safety (θ) More Safe ↔ Less Safe FIGURE C-1  Characteristic curves showing on the y-axis the probability of re ceiving a given violation (at a single inspection)
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From page 148...
... 148 IMPROVING MOTOR CARRIER SAFETY MEASUREMENT TABLE C-1  α, β, and Prevalence for the 20 Violations with the Highest α, Value Generated from Binomial Item Response Theory Description Alpha Beta Prevalence Speeding 0.931 –11.2 10 Following too close 0.871 –5.5 3010 Lane restriction violation 0.839 –4.5 8328 State-local laws operating a CMV while texting 0.833 –8.9 95 Inattentive driving 0.771 –11.0 12 State-local laws speeding 6-10 miles per hour over limit 0.760 –3.6 18946 Operating a CMV while texting 0.734 –9.6 47 Driving a CMV while texting 0.635 –8.8 111 Improper lane change 0.631 –5.3 3614 Failing to use seat belt while operating a CMV 0.627 –4.7 6532 State-local laws speeding 11-14 miles per hour over limit 0.620 –4.7 6629 Using a handheld mobile telephone while operating a CMV 0.568 –5.5 2752 Allowing or requiring driver to use a handheld mobile 0.565 –10.4 20 telephone Failure to slow down approaching a railroad crossing 0.540 –11.4 7 State-local laws speeding in work/construction zone 0.530 –5.8 2134 Failing to stop at railroad crossing bus 0.489 –11.3 8 State-local laws speeding 15+ miles per hour over limit 0.459 –5.3 3549 Railroad grade crossing violation 0.441 –10.4 21 Improper passing 0.426 –7.3 463 Scheduling run to necessitate speeding 0.400 –10.7 15 NOTE: CMV, commercial motor vehicle.
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From page 149...
... Larger values of q correspond to less safe carriers. G GG G G Crashes per 100000 VMT G 0.2 G G G G G G G G G G G G G G GG G G G G G GG G G GGG G G G G G G GG 4.0 G G GG G GG G G G G G G G G G G GG G G G G G G G G G G GGG G G GG G G GG G G G G G G GG G G G G G GG GG G G G G G GG G GGG G G 3.5 G GG GG G G G G G G G G G G G G G G G G G G G G GGG GGG G G G GG G GG G G G GG G GGG G G G GG G G G GG G G G G G G GGG GG G G GG G G GG G G G G G GGG G G G G G G GG G GGGGG GG G GG GG G GGGG G G G G G G G G G G G GG G G GG G G 3.0 G GG GG G G GGGG GG G GG GGG GGGG GGG GGG G G G GG G G G G GGG G G 0.1 GG G GGG G G GG G G G G G GG G G GG G G G 2.5 G G G G GGG GGG GG G G G G GG GG G GG GG G G G G GG G G GG G GG G G G G GGGGG G GGG G G GG GG GG G GG G GG G G G GG G G G G GG G G GG GG G G G G G GGG G G G GGG GG GG G GG G G G GG GGGGGGG GG GG G G GG G G G GGGGGGG GGGGGGGG G G G GG G GGGG 2.0 GG GG G G G GG G GG G G G G GG G G GG G G G GG G G GG G G G G GG G GGG G GG GG G G G G G GGG GG GGGGGGG G G G G G G GG G G GG GGGGGGG G G GG G G GG G G G GG G GG GG G GG G G G GGG GG G G G G GG G G G G G G G G GGGGGGGGG GGG G G GG G G G GG G GGG G G GG G G G G G G G G G G G G GG G G G G G GG G G G GG G G GGG GG G GG G G G GG G G G G G G G GG GG G G G G G G GG GG G G G G G G GG G G G G GG G G G G G G G G G G G G G GG GGG G G GG G G G G G GG G G G G G G G G G G G G G GG GG G G G G G G G GG G G G G G G G G G GG G G G GG G 0.0 G G G GGGG G GGG GGG G G G −7.5 −5.0 −2.5 0.0 Underlying Carrier Safety (θ)
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From page 150...
... . edstan: Stan models for item response theory, version 1.0.6.
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Key Terms

  • driving violations
  • item response
  • response theory
  • motor carrier
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  • binomial item
  • carrier safety
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  • miles traveled
  • vehicle miles

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  • carrier management
  • safe figure
  • apu reported
  • power units
  • development team

  • stan development
  • irt model
  • ggggggggg ggg
  • underlying carrier
  • latent safety

  • plots unsafe
  • ggggg ggggg
  • ggggg ggg
  • binomial irt
  • ggg ggggggg


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