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> That data absolutely does show an increase in deaths Please be careful about removing the word 'excess' here. The word 'excess' is important, as it implies s

> That data absolutely does show an increase in deaths Please be careful about removing the word 'excess' here. The word 'excess' is important, as it implies statistical significance (and is commonly understood to mean that - https://en.wikipedia.org/wiki/Excess_mortality https://en.wikipedia.org/wiki/Excess_mortality). I didn't argue that there was no change in the number of deaths, and I did not say that the table does not show any change in the number of deaths. If your contention is that the sample size is too small, we can actually look at the full population data: https://en.wikipedia.org/wiki/Motor_vehicle_fatality_rate_in_U.S._by_year https://en.wikipedia.org/wiki/Motor_vehicle_fatality_rate_in... Notably, although 2002 had a higher number of fatalities, the number of miles traveled by road also increases. However, it represents a continuation of a growing trend since 1980 which continued until 2007, rather than being an exceptional increase in distance travelled. Also, while 2002 was the worst year since 1990 for total fatalities, 2005 was worse. Fatalities per 100 000 population in 2002 was 14.93, which was around a 1% worsening from the previous year. But 2002 does not really stand out, similar worsenings happened in 1988, 1993, 1994, 1995, 2005, 2012, 2015, and 2016 (to varying degrees). One other observation is that in 2000, there was a population increase of 10 million (from 272 million to 282 million), while other years on either side are pretty consistently around 3 million. I'm not sure why this is the case, but if there's a change in the denominator in the previous year, this is also interesting if we're making a comparison (e.g. maybe the birth rate was much higher due to parents wanting 'millenial babies', none of whom are driving and so less likely to be killed in a crash, again, just a random thought, not a real argument from my side that I would try to defend). The reason 'statistical significance' is important is because it allows us to look at it and say 'is there a specific reason for this, or is this within the bounds of what we would expect to see given normal variation?'. The data don't support a conclusion that there's anything special about 2001/2 that caused the variation.

lmm 2y ago
So what is your actual model here? Do you believe that the rate of injuries didn't actually go up (despite the statistically significant evidence that it did), that some mysterious mechanism increased the rate of injuries without increasing the rate of deaths, or that the rate of deaths really did increase, but not by enough to show in the stats (which are much less sensitive to deaths than to injuries, just because deaths are so much rarer)? I know which of those three possibilities I think is more plausible.
- d1sxeyes 2y ago
  We are talking about excess deaths, not injuries. It feels like the direction you are taking is going further and further away from the original point, and you are misrepresenting what I have said to fit your argument. I did not say that injuries did not go up. I did not say that the rate of deaths did not go up. I did not say that the rate of deaths did not “show in the stats” (unless by that you mean “was not statistically significant”). I don’t need a model for the injuries question because that isn’t the point we’re arguing, but I might suggest something like “after 9/11, people took out more comprehensive health insurance policies, and so made claims for smaller injuries than they would have in previous years”. A suitable model for explaining excess deaths might be something like “after 9/11, people chose to drive instead of fly, and driving is more dangerous per mile than flying is, resulting in excess deaths”. I’m not sure if that is your exact model, but it’s typically what people mean, happy for you to correct. The problem with that model is that there’s no statistically significant increase in miles driven either. I can’t think of a model which would explain a higher fatality/injury rate per mile driven. Out of interest, what would be your model for explaining why there were more injuries per mile? If you found a single story of someone deciding to drive instead of take a plane in October 2001 because of 9/11, and that person died in a car crash, would that be enough for you to be satisfied that I am wrong?
  - lmm 2y ago
    > The problem with that model is that there’s no statistically significant increase in miles driven either. I can’t think of a model which would explain a higher fatality/injury rate per mile driven. > Out of interest, what would be your model for explaining why there were more injuries per mile? Well, is there a statistically significant difference in the injuries per mile? Or even a difference at all? That the difference in injuries was statistically different and the difference in miles driven wasn't does not imply that the former changed by a larger proportion than the latter. Pretty much everyone including all of the papers we've talked about assumes there was an increase in driving. Do you actually think driving didn't increase? Or is this just another area where these concepts of "statistically significant" and "excess" are obscuring things rather than enlightening us? > If you found a single story of someone deciding to drive instead of take a plane in October 2001 because of 9/11, and that person died in a car crash, would that be enough for you to be satisfied that I am wrong? I'm interested in knowing whether deaths actually increased and by how much; for me statistical significance or not is a means to an end, the goal is understanding the world. If we believe that driving did increase, then I don't think it's a reasonable null hypothesis to say that deaths did not increase, given what we know about the dangers of driving. Yes, it's conceivable that somehow driving safety increased by exactly the right amount to offset the increase in driving - but if that was my theory, I would want to actually have that theory! I can't fathom being satisfied with the idea that injuries somehow increased without increasing deaths and incurious not only about the mechanism, but about whether there really was a difference or not. All of these things - miles driven, injuries, deaths - should be closely correlated. If there's evidence that that correlation actually comes apart here, I'm interested. If the correlations hold up, but the vagaries of the statistics are such that the changes in one or two of them were statistically significant and the other wasn't, meh - that happens all the time and doesn't really mean anything.

lmm 2y ago

So what is your actual model here? Do you believe that the rate of injuries didn't actually go up (despite the statistically significant evidence that it did), that some mysterious mechanism increased the rate of injuries without increasing the rate of deaths, or that the rate of deaths really did increase, but not by enough to show in the stats (which are much less sensitive to deaths than to injuries, just because deaths are so much rarer)? I know which of those three possibilities I think is more plausible.

d1sxeyes 2y ago
We are talking about excess deaths, not injuries. It feels like the direction you are taking is going further and further away from the original point, and you are misrepresenting what I have said to fit your argument. I did not say that injuries did not go up. I did not say that the rate of deaths did not go up. I did not say that the rate of deaths did not “show in the stats” (unless by that you mean “was not statistically significant”). I don’t need a model for the injuries question because that isn’t the point we’re arguing, but I might suggest something like “after 9/11, people took out more comprehensive health insurance policies, and so made claims for smaller injuries than they would have in previous years”. A suitable model for explaining excess deaths might be something like “after 9/11, people chose to drive instead of fly, and driving is more dangerous per mile than flying is, resulting in excess deaths”. I’m not sure if that is your exact model, but it’s typically what people mean, happy for you to correct. The problem with that model is that there’s no statistically significant increase in miles driven either. I can’t think of a model which would explain a higher fatality/injury rate per mile driven. Out of interest, what would be your model for explaining why there were more injuries per mile? If you found a single story of someone deciding to drive instead of take a plane in October 2001 because of 9/11, and that person died in a car crash, would that be enough for you to be satisfied that I am wrong?
- lmm 2y ago
  > The problem with that model is that there’s no statistically significant increase in miles driven either. I can’t think of a model which would explain a higher fatality/injury rate per mile driven. > Out of interest, what would be your model for explaining why there were more injuries per mile? Well, is there a statistically significant difference in the injuries per mile? Or even a difference at all? That the difference in injuries was statistically different and the difference in miles driven wasn't does not imply that the former changed by a larger proportion than the latter. Pretty much everyone including all of the papers we've talked about assumes there was an increase in driving. Do you actually think driving didn't increase? Or is this just another area where these concepts of "statistically significant" and "excess" are obscuring things rather than enlightening us? > If you found a single story of someone deciding to drive instead of take a plane in October 2001 because of 9/11, and that person died in a car crash, would that be enough for you to be satisfied that I am wrong? I'm interested in knowing whether deaths actually increased and by how much; for me statistical significance or not is a means to an end, the goal is understanding the world. If we believe that driving did increase, then I don't think it's a reasonable null hypothesis to say that deaths did not increase, given what we know about the dangers of driving. Yes, it's conceivable that somehow driving safety increased by exactly the right amount to offset the increase in driving - but if that was my theory, I would want to actually have that theory! I can't fathom being satisfied with the idea that injuries somehow increased without increasing deaths and incurious not only about the mechanism, but about whether there really was a difference or not. All of these things - miles driven, injuries, deaths - should be closely correlated. If there's evidence that that correlation actually comes apart here, I'm interested. If the correlations hold up, but the vagaries of the statistics are such that the changes in one or two of them were statistically significant and the other wasn't, meh - that happens all the time and doesn't really mean anything.