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Comment by patcheudor | Hacker News Reader

The key point is that you can say things like, "per million miles, Tesla auto pilot use has resulted in X fewer fatalities", however, unless the data leading to that statement has been normalized against data representing the exact use case of Tesla auto pilot then it is false. The only way to say that Tesla autopilot is safer per million miles than a human is to base the figure on when the Tesla auto-pilot could be used. I'm not sure I've ever seen that data from Tesla. Who knows, maybe they have it and I've just not seen it. If they do, very cool. I would assume they could get the data by taking sensor readings from Tesla cars under human control in situations where auto-pilot could be used.

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The NHTSA found a 40% safety improvement when comparing Teslas with Autopilot to Teslas without. I wouldn't put a huge amount of stock in the exact number, but because one group never uses Autopilot and the other offers a realistic view of when people actually do use Autopilot, it seems like enough to say "Yes, Autopilot makes cars safer in aggregate."

The data is suspect at best and should require a third party evaluation. I'm speculating that the reason for that 40% safety improvement is more a result of the difference between where autopilot can and cannot be used. People with autopilot equipped Tesla vehicles get the option because they likely drive more highway miles where it can be used mile after mile. Those who don't, likely don't and may be in statistically more dangerous driving situations like short commutes over high speed roads. When I commuted to the office, I'd pull out of my 25 MPH subdivision road and immediately accelerate to 65-70 MPH onto the highway and proceed to drive two miles. There's no reason for autopilot in those conditions so I wouldn't purchase the package, but yet making a left-hand turn onto a five lane highway where cars are regularly traveling at high speed is one of the more dangerous things you can do while driving for which if I got hit in a side impact could easily be killed and because of the location on a highway, would be counted as a highway fatality.

> The data is suspect at best and should require a third party evaluation.

And the NHTSA doesn't count as a third party?

> I'm speculating that the reason for that 40% safety improvement is more a result of the difference between where autopilot can and cannot be used.

To say that tesla owners without autopilot tend to drive in situations with 40% more likelihood of accidents than those with autopilot, sounds like a massive stretch without data of your own.

I think you misunderstand the data. This isn't "people who opted into Autopilot vs. people who opted out" — the no-Autopilot group is people whose Teslas were made before Autopilot was introduced.

And therefore obviously this is not an unbiased control group. Perhaps the more recent teslas have slightly better/less used brakes? Have they controlled for that? There are countless ways in which such conclusions can be flawed.

Statistics is really tricky, even with very large samples at recent presidential election had shown that beyond any doubt.

You are making an incorrect assumption. When Tesla released their original Autopilot, it was a no-charge SW update for all cars equipped with the necessary hardware (which was all cars built within the previous xx months). Thus, the drivers with Autopilot capability were driving the same commute in non-Autopilot capable cars the day before. There was no customer selection based on perceived utility of Autopilot.

How many fatal collisions did they use in this dataset? This can't be a serious assessment.

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