During 2013–2017, casualty rates per 100 million miles were 5.16 (95% CI 4.92 to 5.42) for E- HE vehicles and 2.40 (95%CI 2.38 to 2.41) for ICE vehicles, indicating that collisions were twice as likely (RR 2.15; 95% CI 2.05 to 2.26) with E-HE vehicles. Poisson regression found no evidence that E-HE vehicles were more dangerous in rural environments (RR 0.91; 95% CI 0.74 to 1.11); but strong evidence that E-HE vehicles were three times more dangerous than ICE vehicles in urban environments (RR 2.97; 95% CI 2.41 to 3.7). Sensitivity analyses of missing data support main findings.
Wait, are the cars themselves are twice as likely to hit pedestrians, or are the drivers of the cars twice as likely to hit pedestrians?
That’s a fair question regarding clarity — the authors of the study touched on this in the “Strengths and weaknesses of the study” section:
The study is technically looking at the unit of driver and vehicle, rather than only the driver or only the vehicle, so the results could potentially be different if the driver and car are viewed as a unit rather than separate.