Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Heuristics that almost always work

astralcodexten.substack.com

Post reply on HN
Print view View original

461–470 of 541 posts

Re: Heuristics that almost always work

#461

Post by ccalloway »

thehappypm wrote: post #185
gpm wrote: post #115

Earlier quoted context omitted.

1:5000 would suggest an average lifetime of 13.7 years for a grown tree (i.e. not counting the years where it's too young to sleep under), and that's before the ability to avoid trees that look more likely to fallover. I don't know anything about trees around there, maybe they're really short-lived? For forests around here, it's a gross overestimate.

Somehow I suspect trees in Papa New Guinea are different than the trees where you are

or perhaps the main difference between Papua New Guinea and the GP's location is that people feel entitled to make up weird questionable stories about PNG and not about their place.

Re: Heuristics that almost always work

#462

Post by withinboredom »

mort96 wrote: post #246
gpm wrote: post #115

Earlier quoted context omitted.

1:5000 would suggest an average lifetime of 13.7 years for a grown tree (i.e. not counting the years where it's too young to sleep under), and that's before the ability to avoid trees that look more likely to fallover. I don't know anything about trees around there, maybe they're really short-lived? For forests around here, it's a gross overestimate.

Remember that the relevant set isn't the set of all trees, but the set of trees old enough to be large enough to sleep under. That means the average lifetime would be: (number of years it takes for a tree to become big enough to sleep under) + 13.7. I would still guess that the number is wrong, I suspect that trees have a longer life on average from becoming what we would consider "big" until they fall over. But it's…

I mean “big enough to sleep under” is around 50+ years for most hardwoods IIRC. Also, you have to consider groups of trees that can fall on you in the surrounding area. So it’s really the probability that a tree falls within any given 50m radius, towards the center. I think the stated probability is pretty accurate. Also as humans, we tend to pick trees that provide the best shelter, thus older. From experience, if one of those big older branches decide to fall, you don’t want to be underneath. As a kid, a huge oak tree lost a huge branch right in front of me. It scared the crap out of my 8yr old self, so much that I still remember it quite vividly, it would have killed my brother and I if we hadn’t just moved out of the area. The limb looked perfectly healthy btw, green and all. There was no indicating factors, according to the adults at the time.

Re: Heuristics that almost always work

#463

Post by notahacker »

ccalloway wrote: post #460
inglor_cz wrote: post #30

This story reminded me of a story written by a Czech biologist who studied animals in Papua-New Guinea and went to a hunt with a group of local tribesmen. The dusk was approaching, they were still in the forest and he proposed that they could sleep under a tree. The hunters were adamant in their refusal: no, this is dangerous, a tree might fall on you in your sleep and kill you . He relented, but silently considered…

It seems like 1:5000 is not an accurate probability, but just a number which he chose in order to convince himself that sleeping under a tree was not a risky activity. But he chose a bad number and later realized that an argument based on that number was not convincing. If the chance was actually 1:5000, the longevity of trees would be similar to that of hunters sleeping under them - or lower, since hunters can somet…

Takes the whole tree collapsing to kill the tree. A large enough branch (or a coconut, if we're on Papua) should suffice for a hunter.

Re: Heuristics that almost always work

#464

Post by notahacker »

fastball wrote: post #390
dragontamer wrote: post #332

Earlier quoted context omitted.

The Hydroxychloroquine discussion is pretty bad as well. We were confidently against Hydroxychloroquine because it was well tested in the RECOVERY trial in June 2020 [1]. The time to be optimistic was during the trial-phase of the test. Once that time passed, everything beyond that point was unnecessary and unhelpful hype. ------ What's amazing to me, is that the RECOVERY trials showed that Dexamethasone cut the deat…

I think you missed the point. The idea here is that there were people that said before any results were in that hydroxychloroquine was not gonna work, operating with a heuristic that almost always works. And in this case they were correct, which the article doesn't seem to disagree with. The point is that at some point the heuristic will fail, not that it did in the case of hydroxychloroquine.

But it's worth pointing out that (i) the medical profession, who are the appropriate people to be evaluating HCQ, didn't rely on their heuristic but did the test and (ii) if you as a layman abandon the heuristic that you shouldn't be receptive to the advice of conspiracy theorists and alternative therapists protesting the medical profession because they might be right about something, following that advice isn't largely cost-free unlike the other examples Scott Alexander set up, and is in fact more likely to harm you than the heuristic

Re: Heuristics that almost always work

#465

Post by xelxebar »

borroka wrote: post #370
hacknat wrote: post #349

Earlier quoted context omitted.

Are you reading the deeper lesson though? The individual examples aren't meant to be authoritative. He was trying to illustrate the very thing you are bringing up. Namely that lazy heuristics create information cascades. The information cascades can have positive effects, as you point out, but they can have profoundly negative consequences, which is the point of the whole article. We shouldn't use or intellectually t…

"On your doctor take, you do know that the other author of this post is a licensed and practicing Physician, right?" -- Your observation is indeed much more interesting than the whole article, since it shows a reasonable (and not a caricature with zero value) heuristic. You are saying that I (who may or may not be a physician, but for argument's sake let's say I am not) should not have an opinion that is different, w…

Perhaps it could be more helpful to think of the caricatures as "spherical cow" models the author is using when trying to isolate and illustrate a particular social (?) dynamic.

Of course real-world models will be much more nuanced, but the really interesting bit is that you don't need all that nuance to produce the particular pathology outlined in the article. Specifically, selecting on "who is most right most of the time?" can end up causing your city to be covered in lava, missing a store break-in, or what-not.

There are even more levels to explore with this idea. For example, should you always ignore the heuristics and go for the earest, honest experts? Maybe. In the volcano example, the cost of a false negative is so high that you probably are okay with the incurred costs of false positives by the experts.

However, in the case of the Futurist, the false-positives incurred for a non-rock opinion might end up netting you less karma points or whatever. It's somewhat fun doing a re-read trying to evaluate the cost-benefit tradeoff yourself in each case!

Re: Heuristics that almost always work

#466

Post by coldtea »

blunte wrote: post #430
derbOac wrote: post #156

Earlier quoted context omitted.

"There are bold X, and old X, but no old, bold X." Replace X with any practitioners subject to sufficient risk as a result of their practice. I first heard it in the context of mushroom foraging.

There's chance of death, but there's also duration of suffering while dying. I'm guessing that falling from a cliff is "better" than dying from a poisonous mushroom. The latter scares the hell out of me. The former is a glorious ride until the ride is over (regrettably).

>The former is a glorious ride until the ride is over (regrettably).

If you sense you're falling to death, it wont be too glorious (personally), but freakish. It can also always fail to bring death!

Re: Heuristics that almost always work

#467

Post by kstenerud »

> The only problem is: he now provides literally no value. He’s excluded by fiat the possibility of ever being useful in any way. He could be losslessly replaced by a rock with the words “THERE ARE NO ROBBERS” on it.

Not true. His value is in being there. He's not there to stop robbers, but rather to stop squatters or mischief makers who are looking for something to do (in which case there will be a lot more than just some odd noise). Nobody in a first world country is going to rob a pillow mart.

> Her heuristic is right 99.9% of the time, but she provides literally no value. There is no point to her existence. She could be profitably replaced with a rock saying “IT’S NOTHING, TAKE TWO ASPIRIN AND WAIT FOR IT TO GO AWAY”.

Also not true. If there's a real problem, it won't go away and the patient will return, either with no improvement, or a worsening of symptoms.

> It cannot be denied that the employees he hires are very good. But when he dies, the coroner discovers that his head has a rock saying “HIRE PEOPLE FROM GOOD COLLEGES WITH LOTS OF EXPERIENCE” where his brain should be.

But he hires good people for his company. So regardless of the soundness of his methods, he is providing value to that company.

Followed by a bunch more contrived examples and downright black swan events.

Bottom line: Yeah, they're using heuristics that will sometimes be wrong, but life itself is about compromises. There's no such thing as perfect information, so we use heuristics out of necessity. Worrying about the unlikely scenario is a recipe for paralysis.

Re: Heuristics that almost always work

#468

Post by jnordt »

Great article and examples.

In the security guard story: I understand the point that the author is trying to make, but it falls short as the security guard adds value to the property owner by just being phsysically there.

By being present the chance of a robbery, vandalism etc is significantly reduced. In most countries the average guard is also not expected to actually intervene with a robbery and instead call police (the US might be an exception here in some cases).

Re: Heuristics that almost always work

#469

Post by ccalloway »

notahacker wrote: post #463
ccalloway wrote: post #460

Earlier quoted context omitted.

It seems like 1:5000 is not an accurate probability, but just a number which he chose in order to convince himself that sleeping under a tree was not a risky activity. But he chose a bad number and later realized that an argument based on that number was not convincing. If the chance was actually 1:5000, the longevity of trees would be similar to that of hunters sleeping under them - or lower, since hunters can somet…

Takes the whole tree collapsing to kill the tree. A large enough branch (or a coconut, if we're on Papua) should suffice for a hunter.

The hunters said 'a tree might fall on you and kill you'? This is supposed to be a nugget of ancient wisdom. Now it turns out it's actually a coconut falling out of the tree? Are you providing this extra information? Or was it somehow implicit in the original telling?

Is it possible that both the original teller, the reteller and you too, are starting from the (unfounded) assumption that the hunters know what they're talking about, and are adapting the facts to fit this assumption?

Re: Heuristics that almost always work

#470

Post by chimprich »

yodsanklai wrote: post #252
kbuchanan wrote: post #35

Earlier quoted context omitted.

It's a great example. This is the very reason I have scaled back the amount of time I rock climb as I've gotten older -- not because any individual outing is dangerous, but there's an element of Russian roulette wherein the mere act of doing it more often dramatically changes the risk.

That's the reason why I don't cycle in London. When I moved there, I thought I would be using my bike daily like I was used to. But over the span of a few years, I'm pretty sure the risk of serious injury becomes significant. For rock climbing, you're probably right. I remember training in a climbing hall, when I saw someone falling off the highest wall. The tenant of the hall didn't look surprised at all. Apparently…

You can contrast the odds of getting injured with the health benefits. The cardiovascular benefits would seem to outweigh the risks of getting injured from a mathematical point of view.

See e.g. https://blogs.bmj.com/bjsm/2018/12/12/pedal-power-the-health...

Post reply on HN