Main question: Why does a particular highway have roughly the same number of automobile-related deaths every year if a car crash is unexpected and dependent on the actions of individual drivers?
More detail: in Tennessee, they have those electronic signs on the interstate that occasionally show the number of roadway fatalities in the state for the current year and beneath that it will show the previous year. The numbers are almost always close, within a reasonable margin of error and accounting for both slightly more drivers on the road each year fur to population growth.
Having been in a serious car crash, I understand the seemingly arbitrary way a sequence of events can play out depending on multiple factors such as driver awareness, vehicular dependency, roadway conditions, weather, etc. Even a highly skilled and fully focused driver in a perfectly functional car on a road with no issues can be involved in a crash, say due to a different driver’s condition, a deer running out into the road, or a sudden gust of wind blowing a newspaper onto their windshield and obscuring their vision for a few seconds.
This may by a multi-part question, but it’s been in the back of my mind for years now and I woke up today wondering about radioactive decay so I started reading about isotope decay. That’s not really what this question is about though, but the seemingly random probability of an isotope decaying in an independent manner (not related to the actions of any other isotopes nearby) made me kind of connect these two ideas and start to wonder about it again.
So getting back to the roadway fatalities, in this case for the state of Tennessee, I found the 20 year statistical data at the site linked below. It shows some ups and downs over the years, presumably with the reductions coming from improved safety features in cars, yet the total number for 2020 (1,221) is closer to the total for 2001 (1,251) than it is to the total for even the previous year 2019 (1,148).
So despite population growth and enhanced safety features, we are kind of right back where we started, or rather, where we’ve always been.
I could also expand this question to cover other events that should ideally never occur, such as murder. Why does something as abominable and world-shattering like murder, at least from an individual perspective, happen with roughly the same frequency and rate when looking at a large sample size? Shouldn’t something like that be the exception and not the norm? Is it somehow related to density?
This has me wondering about probability, fate, design, and all sorts of things both rational and irrational.
Anyway, thanks for reading this. Even if nobody responds, I think it’s helped to just get it out in writing for the next time I think about this in a few months.
TLDR: Why do independent actions and events that deviate from the norm happen with almost certain predictability?
In: Mathematics
Thank you to everyone who has answered so far, I really appreciate your insight and responses. The car crash thing makes a little more sense now, but I’m still a bit stuck on the homicide numbers being roughly equal every year. I could see them remaining stagnant if the killers are never caught, which allows the same people to continue killing year after year. And I know some cities do have low solve rates for murder, but if we could magically find out who was behind every murder somehow, I believe statistically there would be extremely few repeat offenders in the larger sample size.
I guess the underlying question in my mind, from a problem-solving point of view, is how can we as a society reduce those factors that contribute in larger ways to these undesirable events like roadway fatalities and murder?
What is the largest population size possible to not have a single murder in any given year? I know small villages and towns around the world can go decades without a single murder, so it’s not impossible in a relative microcosm of larger society. And I remember from anthropology class that someone determined a long time ago that the optimum number of people in any given living area is something like 12 to 18 people per square kilometer or something. I may be misremembering but basically it was determined that bad things start to pop up due to inherent human nature when we exceed that number.
So is it primarily a matter of population density that drives up the murder rate? I could probably understand that. Of course there are abberant genetic factors that can predispose individuals towards violent behavior which we can more easily correlate to a statistical model, basically turning psychology into biology and mathematics.
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