Driving fatalities on US presidential election days: a reanalysis.

Fan Zhang,Peter M Aronow

doi:10.1186/s13104-016-2148-6

Abstract

BackgroundRedelmeier and Tibshirani reported a statistical analysis in the Journal of the American Medical Association in 2008 indicating that presidential election days are strongly associated (P < 0.001) with an increased risk of driving fatalities (as measured by the number of persons involved in fatal crashes).FindingsWe present evidence indicating that the risk of driving fatalities on presidential election days is neither statistically nor substantively unusual. Although we find weakly suggestive evidence that presidential elections may increase the risk of driving fatalities during election hours, any increase appears to be entirely offset by a lowered risk during non-election hours.ConclusionsWe find weaker support for an association between election days and driving fatalities than was previously reported. Our results suggest caution in evaluating policy prescriptions that presuppose that election days pose an unusual risk to the public.

Highlights

Redelmeier and Tibshirani reported a statistical analysis in the Journal of the American Medical Association in 2008 indicating that presidential election days are strongly associated (P < 0.001) with an increased risk of driving fatalities
Given this positive association between election days and driving fatalities, Redelmeier and Tibshirani (RT) concluded that the results suggest that policy interventions are warranted to alleviate the increased risk posed by election days
We estimated relative risk (RR) for the 100 Tuesdays before and after presidential election days. (We restrict ourselves to Tuesdays as all United States presidential elections are held on Tuesdays, conditioning on any day-of-week effects.) Using these 200 RRs, we constructed an empirical null distribution, with non-parametric two-tailed P values computed as the proportion of RRs more extreme (i.e., RR greater or 1/RR smaller) than that of presidential election days

Summary

Conclusions

We find weaker support for an association between election days and driving fatalities than was previously reported. Our results suggest caution in evaluating policy prescriptions that presuppose that election days pose an unusual risk to the public. Findings Redelmeier and Tibshirani [1], RT, reported a statistical analysis indicating that presidential election days are strongly associated (P < 0.001) with an increased risk of driving fatalities. Given this positive association between election days and driving fatalities, RT concluded that the results suggest that policy interventions are warranted to alleviate the increased risk posed by election days. We sought to replicate and extend these results to reassess both the robustness of RT’s results and the implications for policy making

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Discussion