Public Transit is not Infinitely Safe

For what it's worth, the 2022 CTA homicides were a huge outlier. The years 2001-2019 had 0-2 homicides each (filtering "CTA" in "Location"), then 4 in 2020 and 4 in 2021. Meanwhile, leading up to the pandemic, the National Transit Database says Passenger Miles Traveled was approaching 2 billion (https://www.transit.dot.gov/ntd/transit-agency-profiles/chicago-transit-authority), was down to 800 million for 2020 and 2021, and presumably came back up a lot in 2022 (no profile available yet).

I agree it's not infinitely safe, but I do suspect transit comes out safer by most analyses.

2001 0
2002 0
2003 1
2004 2
2005 0
2006 0
2007 1
2008 2
2009 1
2010 0
2011 2
2012 0
2013 1
2014 0
2015 0
2016 1
2017 2
2018 2
2019 2
2020 4
2021 4
2022 9
2023 2 (partial; annualizes to ~5)

I recall hearing that a large percentage of homicides are done by someone the victim is close with. And then I presume a big chunk of the remaining homicides are gang or drug related. After that, I suspect that common sense and being the bigger person in an argument goes a very long way. I suspect that once factored in, this stuff would reduce the rate by 3-5 orders of magnitude.

For cars, I'm not sure how much we can cut the death rate by not doing dumb things like drinking and driving. Given that there's about a 2.5-to-1 ratio of alcohol to non-alcohol-related deaths, I feel like being a good driver probably only cuts your risk by, at most, a factor of 2 or 3. Not an order of magnitude. It's hard because you can do everything right and end up dead because of someone else. There's only so far that defensive driving takes you.

With these two assumptions, public transit starts to look a lot safer.

All comparisons like this are completely misleading, because they're based on averages across widely variant situations and people.  It's a BIG hint that you're talking about transit homicides vs automobile death by collision.  The two biggest determinants of safety for this decision are NOT "for the median trip, which mode has fewer deaths?", but "for you personally right now, are you drunk, and/or are you involved with often-violent people?".

Sure, there are many car deaths where the traveler is not drunk, and some transit deaths (unclear if you're counting the walk and wait portions, or only on the transport, but it doesn't matter) of uninvolved bystanders.  But they're only a fraction of the reported statistics, small enough that the comparison falls apart.

For this decision, like MOST choices in life, variation is so great that you really can't update on averages.

 I'm not sure how to get to a place where we see fewer bold false claims, but a culture of giving sources, and supporting requests for them, seems like it would help? 

A culture of giving sources and supporting requests for them is a culture of "doing your own research". Over the last years, the ideology of the censorship industrial complex is that "doing your own research" is bad and that people should instead believe in the authorities. No mainstream media outlet would run an OPed titled "In defense of doing your own research". 

Culturally, many people believe that it's important to trust in authorities instead of make statements in support of the mainstream narrative. 

This leads to strange effects such as posts on skeptics.stackexchange that ask whether certain antivaxx claims are true getting downvoted in a way that they wouldn't have five years ago because investigating whether nonmainstream claims are true was part of the point of skeptics.stackexchange.

Actually, advocating for a culture of "doing your own research" is not going to be an easy project. 

You could add a community note to that tweet. I think that's a pretty good tool to correct and discourage such claims on Twitter.

I'm not sure how to get to a place where we see fewer bold false claims, but a culture of giving sources, and supporting requests for them, seems like it would help?

Are there any networks on mastodon that are actually capable of maintaining the incentives, the level of accountability, that it takes, to stop spreading misinformation? Because I'm not aware of any, but [looks] a MIT instance would be a very credible candidate? Is it quite good?

I don't really think it's worth trying to save microblogger cultures, the microblogging format inherently encourages oversimplification, rapid spread, and it's profoundly hostile to real conversation. Personally I'd recommend contributing to the construction of better systems like bonfire.networks instead.

there were 0.71 driving deaths per 100M miles travelled

I don't think this is a good basis for comparison. The comparison in the tweet you link to seems to talk about commuting, so it would probably make sense to compare based on the number of trips rather than based on the miles traveled. In particular, in the data you link to, we can see that the number of car accidents from trucks is pretty small, while I would guess that truck drivers represent a bigger share of miles traveled, thus lowering the death rate per mile, without this being relevant information.

[EDIT] I looked it up

For public transit, you write (for a high crime rate city, but not the highest possible, and for an outlier year, as pointed out in another comment) 

This is 3.7 homicides per 100M trips.

In the US, there are about 400 billion car trips per year, and about 40k death per year, so this implies an average death rate of 10 death per 100M trips. This is an average. 

4 of the 9 homicides occurred on CTA property, but not on trains or buses. Does that mean you should include all homicides that occur on streets, driveways and parking lots?

Focusing on only deaths makes some sense since it's the largest likely harm, but I will note that death is not the only outcome some people are afraid of on public transit; if you include lesser harms like being mugged or groped then that is going to tip the scales further towards driving since those things have a ~0% chance of happening while driving, and a small-but-probably-non-trivial chance (I haven't looked it up) on transit.

You shouldn't be comparing only HOMICIDES, the point of this comparison is that you are much more likely to die (from any cause, most likely from an automobile accident) than you are to die while taking public transit (from any cause). Homicide may be the most likely cause of death while taking public transit (or it may not), but I imagine the odds of getting killed in an accident while driving present a much greater risk.