Tesla’s Driver Fatality Rate is more than Triple that of Luxury Cars • Hacker News Board

Re: Tesla’s Driver Fatality Rate is more than Triple that of Luxury Cars

#21

Post by dahdum » Tue, Jul 24, 2018, 5:06 AM UTC

rgbrenner wrote: post #13

dahdum wrote: post #12

Earlier quoted context omitted.

They found clear Tesla fatalities that were missing from the published data, apparently a significant number of them due to miscategorization. Now maybe all the brands have the same problem with missing data, but that would mean fatalities across the board are much higher than reported by the insurance agency funded research firm. That doesn’t seem as likely to me, but I do believe more research needs to be done.

And then they still didn't like the numbers for the US, so they included China--for tesla only. Do you know how much that changes the numbers? The US had 12.9 fatalities per 100k cars. China? 104.5 -- 8 times higher. Come on. This is a joke.

I'm only seeing 1 fatality from China, does that move the needle substantially in this analysis?

> To have the largest sample size and best confidence intervals possible, we also included international accidents (three total, from Canada, Holland, and China). Given the higher incidence of fatal accidents per vehicle-year in China compared to the United States, and the lower incidence of fatal accidents in Holland and Canada, these three deaths should adjust to 3.63 deaths. However, for the sake of conservatism and to avoid a large debate about a rather small difference, we use 3.00 deaths in our analysis.

Re: Tesla’s Driver Fatality Rate is more than Triple that of Luxury Cars

#22

Post by google_censors » Tue, Jul 24, 2018, 5:11 AM UTC

The author of this article claims to have received an award for at least one published medical study, and I think someone should take a serious look at it. If he thinks that this methodology is okay in a study, I can't imagine what would happen if someone used his medical study for anything but laughs.

Re: Tesla’s Driver Fatality Rate is more than Triple that of Luxury Cars

#23

Post by wjnc » Tue, Jul 24, 2018, 5:20 AM UTC

google_censors wrote: post #19

wjnc wrote: post #14

Earlier quoted context omitted.

So please explain. It's quite a long story but with some good finds (data quality problems, obfuscated reporting, probability of much higher casualty rate). I wonder what your statistical rigour makes of this.

Well, including data from China for only Tesla is a joke. That would be like saying "we couldn't find any deaths from Ebola in the United States, so we took the ones in Africa and added them in. Wow, look at how many deaths per year from Ebola occurred in the US compared to deaths from the plague in the US!". It makes absolutely no sense.

Well it might be. They also include a casualty from NL at face value, while casualties are MUCH rarer here. I agree with the need for discounting of a Chinese casualty, but it's quite common practice to try to get more data points. That is good practice, not bad, and we only seem to disagree with the execution (is a China casualty 1 or .8?) In this case it wouldn't matter the base take-away much.

Re: Tesla’s Driver Fatality Rate is more than Triple that of Luxury Cars

#24

Post by cs702 » Tue, Jul 24, 2018, 5:33 AM UTC

I submitted the OP, and am a bit surprised to see it flagged. The OP looks to me like a sincere attempt to analyze fatality data.

Yes, the authors are short Tesla, but they disclose it. Yes, the analysis is naive, but that doesn't necessarily mean its conclusions are off. Yes, the inclusion of data from China is... questionable, but the authors address it upfront: "To have the largest sample size and best confidence intervals possible, we also included international accidents (three total, from Canada, Holland, and China). Given the higher incidence of fatal accidents per vehicle-year in China compared to the United States, and the lower incidence of fatal accidents in Holland and Canada, these three deaths should adjust to 3.63 deaths. However, for the sake of conservatism and to avoid a large debate about a rather small difference, we use 3.00 deaths in our analysis."

Re: Tesla’s Driver Fatality Rate is more than Triple that of Luxury Cars

#25

Post by dahdum » Tue, Jul 24, 2018, 6:08 AM UTC

cs702 wrote: post #24

I submitted the OP, and am a bit surprised to see it flagged. The OP looks to me like a sincere attempt to analyze fatality data. Yes, the authors are short Tesla, but they disclose it. Yes, the analysis is naive, but that doesn't necessarily mean its conclusions are off. Yes, the inclusion of data from China is... questionable, but the authors address it upfront: "To have the largest sample size and best confidence…

Doesn't deserve the flag IMO, Tesla is an emotional topic for many people. While there certainly have been hit pieces and hack journalism throughout the companies existence, I think this one has enough meat to be worth discussing.

Like most investors, I'm long TSLA. Both index and individual shares.

Re: Tesla’s Driver Fatality Rate is more than Triple that of Luxury Cars

#26

Post by philliphaydon » Tue, Jul 24, 2018, 6:43 AM UTC

cs702 wrote: post #24

I submitted the OP, and am a bit surprised to see it flagged. The OP looks to me like a sincere attempt to analyze fatality data. Yes, the authors are short Tesla, but they disclose it. Yes, the analysis is naive, but that doesn't necessarily mean its conclusions are off. Yes, the inclusion of data from China is... questionable, but the authors address it upfront: "To have the largest sample size and best confidence…

I must be stupid, but what does "Short Tesla" mean?

Re: Tesla’s Driver Fatality Rate is more than Triple that of Luxury Cars

#27

Post by AstralStorm » Tue, Jul 24, 2018, 6:55 AM UTC

wjnc wrote: post #23

google_censors wrote: post #19

Earlier quoted context omitted.

Well, including data from China for only Tesla is a joke. That would be like saying "we couldn't find any deaths from Ebola in the United States, so we took the ones in Africa and added them in. Wow, look at how many deaths per year from Ebola occurred in the US compared to deaths from the plague in the US!". It makes absolutely no sense.

Well it might be. They also include a casualty from NL at face value, while casualties are MUCH rarer here. I agree with the need for discounting of a Chinese casualty, but it's quite common practice to try to get more data points. That is good practice, not bad, and we only seem to disagree with the execution (is a China casualty 1 or .8?) In this case it wouldn't matter the base take-away much.

You have to at least account for differences in base rate of accidents. The typical normalisation would take at least published accident total to synthesise data for the other cars. (By using sales numbers of cars.)

What he did there is statistically unacceptable.

The medical equivalent would be to compare side effect profile of current best of line treatment done in general populace to results to your new treatment's phase 1 trial results which is done in healthy people only. Then advertise that.

Regardless, can we have the raw data please? Are the rates even meaningful when the incident counts are low? Vehicle years are not the right unit as this counts cars that are not being driven. Actual range driven is the right unit.

Re: Tesla’s Driver Fatality Rate is more than Triple that of Luxury Cars

#28

Post by wjnc » Tue, Jul 24, 2018, 7:09 AM UTC

AstralStorm wrote: post #27

wjnc wrote: post #23

Earlier quoted context omitted.

Well it might be. They also include a casualty from NL at face value, while casualties are MUCH rarer here. I agree with the need for discounting of a Chinese casualty, but it's quite common practice to try to get more data points. That is good practice, not bad, and we only seem to disagree with the execution (is a China casualty 1 or .8?) In this case it wouldn't matter the base take-away much.

You have to at least account for differences in base rate of accidents. The typical normalisation would take at least published accident total to synthesise data for the other cars. (By using sales numbers of cars.) What he did there is statistically unacceptable. The medical equivalent would be to compare side effect profile of current best of line treatment done in general populace to results to your new treatment'…

I totally agree. But keep in mind the effect "doing the right thing" has on the effect to be estimated. I venture it will not change the gist of the story. Heck, I should contact the author and build a shiny app to demonstrate. Even discounting a Chinese death 50% would put Tesla in the ballpark double the risk of luxury cars. My thought would be that Tesla is more a supersport car (McLaren, etc) in risk (for some drivers, say, male, young or midlife, etc).

That one local death in NL, the guy did double the allowed speed on a stretch where I can hardly hit 20% above the allowed speed accounting for traffic lights and local situation. The one Tesla death with the young kid, the same. Don't put maximum traction hundreds of HP in male hands. We tend to use it (sometimes).

Re: Tesla’s Driver Fatality Rate is more than Triple that of Luxury Cars

#29

Post by jpatokal » Tue, Jul 24, 2018, 7:10 AM UTC

wjnc wrote: post #14

et2o wrote: post #5

Is this really what passes for statistical analysis in the investment community? From a biomedical statistics background, this analysis so atrocious that I don't know where to start.

So please explain. It's quite a long story but with some good finds (data quality problems, obfuscated reporting, probability of much higher casualty rate). I wonder what your statistical rigour makes of this.

The biggest problem is that they go through all sorts of hoops to add unreported Tesla fatalities to the data, then compare those against unadjusted other fatalities and report that there are "more than Triple" apples (adjusted) vs orange (unadjusted).

The least they could do is run the same stats for both Tesla and another luxury brand (say, Audi), and then compare like to like.

Re: Tesla’s Driver Fatality Rate is more than Triple that of Luxury Cars

#30

Post by AstralStorm » Tue, Jul 24, 2018, 7:17 AM UTC

wjnc wrote: post #28

AstralStorm wrote: post #27

Earlier quoted context omitted.

You have to at least account for differences in base rate of accidents. The typical normalisation would take at least published accident total to synthesise data for the other cars. (By using sales numbers of cars.) What he did there is statistically unacceptable. The medical equivalent would be to compare side effect profile of current best of line treatment done in general populace to results to your new treatment'…

I totally agree. But keep in mind the effect "doing the right thing" has on the effect to be estimated. I venture it will not change the gist of the story. Heck, I should contact the author and build a shiny app to demonstrate. Even discounting a Chinese death 50% would put Tesla in the ballpark double the risk of luxury cars. My thought would be that Tesla is more a supersport car (McLaren, etc) in risk (for some dr…

I suspect the correct use of Chinese data would make error bars overlap, exposing the BS.

Moreover, they should use the data where miles drive is available, say, from taxi drivers. Oops, that's 0 out of 0 total? :)

For such low incidences, even studentising will not produce right confidence intervals based on normal distribution. Poisson distribution cannot even be used, direct binomial instead, because it is likely that the error due to approximation will be important. (calculate from rule of rare events)