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Comment by dns_snek | Hacker News Reader

https://www.forbes.com/sites/stevebanker/2023/12/18/tesla-ha...

and their source: https://www.lendingtree.com/insurance/brand-incidents-study/...

> Tesla drivers have the highest accident rate compared with all the brands analyzed. During the period analyzed, Tesla drivers had 23.54 accidents per 1,000 drivers. Ram (22.76) and Subaru (20.90) were the only other brands with accident rates over 20.00 per 1,000 drivers.

> It’s hard to nail down why certain brands may have higher accident rates than others. However, there are indications that certain types of vehicles attract riskier drivers than others.

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“Accident rates per 1000 drivers” is not a particularly meaningful metric, though. If you look at the per-state breakdown, or the incident rates, the states with the most Teslas (CA, e.g.) don’t have Tesla in first place.

More interesting would be accidents per million miles (a standard metric here) and similar. These are less biased by “who owns what kind of car” and include “who drives a bunch with them”. But of course there are many reasons to want one metric over another, and none is perfect.

Accidents per driver is the only metric that matters, because the one tells you how risky a certain class of drivers is. Accidents per passenger mile is not even meaningful, because you do not decrease the risk by by making more miles.

Ah, except it does not tell you that. Consider this extreme example: if Honda drivers on average drive 200 miles a week and 10% of them get into an accident each year, while Lamborghini drivers on average only take their cars out for a single 10-mile spin once a year but also 10% of them get into an accident each year, it would a poor conclusion to say that these are equivalently risky driver classes.

> Accidents per passenger mile is not even meaningful, because you do not decrease the risk by by making more miles.

Er, right, it is meaningful because you obviously increase the risk by driving more miles. Very easy to own a car and have 0 accident risk: never drive it.

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