All of my analysis comes from the US Bureau of Transportation Statistics, particularly information published in 2024. You are right–It is very, very difficult to normalize the data across different modes, however my analysis is specifically over passenger-miles, but I also did it over passenger-hour exposure, which is significantly worse because you can cover more distance in a shorter amount of time.
I wrote a section on the subject in a paper that is currently under academic review at CHI, but I ultimately cut the section. I should write it into a blog at some point.
Risk assessment is tricky business, and I’ve spent countless hours in discussion with colleagues over the topic. Humans, even highly attuned academics, are inherently terrible at assessing risk for low-frequency events. While we like to say things like one is 3x more likely than the other, it often lacks the context of scale. A lack of context often results in overly cautious recommendations that encourage people to live like a bubble-boy. I’ve advocated in the past that all academic journals should adopt a common risk metric, like the micromort when reporting on risk.
There are 800,000 pilots in the US, and an average of 300 deaths per year or 3.75 per 10,000 pilots. There are 243 million drivers in the US and 40,000 deaths per year, or 1.6 per 10,000 drivers. While one is higher than the other, they are still incredibly small frequency events, and our ape brains are not capable of adequately reasoning over that concept.
Looking at UK government stats the difference is starker here - over 100 deaths per billion passenger miles for motorcyclists, only 3 for car occupants, and 27 for pedestrians.
The note of panic in my mum’s voice when talking about the possibility of my getting a motorbike is still out of proportion though.
All of my analysis comes from the US Bureau of Transportation Statistics, particularly information published in 2024. You are right–It is very, very difficult to normalize the data across different modes, however my analysis is specifically over passenger-miles, but I also did it over passenger-hour exposure, which is significantly worse because you can cover more distance in a shorter amount of time.
I wrote a section on the subject in a paper that is currently under academic review at CHI, but I ultimately cut the section. I should write it into a blog at some point.
Risk assessment is tricky business, and I’ve spent countless hours in discussion with colleagues over the topic. Humans, even highly attuned academics, are inherently terrible at assessing risk for low-frequency events. While we like to say things like one is 3x more likely than the other, it often lacks the context of scale. A lack of context often results in overly cautious recommendations that encourage people to live like a bubble-boy. I’ve advocated in the past that all academic journals should adopt a common risk metric, like the micromort when reporting on risk.
There are 800,000 pilots in the US, and an average of 300 deaths per year or 3.75 per 10,000 pilots. There are 243 million drivers in the US and 40,000 deaths per year, or 1.6 per 10,000 drivers. While one is higher than the other, they are still incredibly small frequency events, and our ape brains are not capable of adequately reasoning over that concept.
Yeah that is important context.
Looking at UK government stats the difference is starker here - over 100 deaths per billion passenger miles for motorcyclists, only 3 for car occupants, and 27 for pedestrians.
The note of panic in my mum’s voice when talking about the possibility of my getting a motorbike is still out of proportion though.