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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 da
by kbuchanan 5y ago
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.
- kqr 5y agoAlso known as the Kelly criterion. If one possible outcome of an action is associated with a great enough loss, it doesn't make sense to perform the action no matter how unlikely the loss.
- PaulHoule 5y agoNo, Kelly is about what fraction of your bankroll you should bet if you want to maximize your rate of return for a bet with variable odds. It's essential if you want to: * make money by counting cards at Blackjack (the odds are a function of how many 10 cards are left in the deck) * make money at the racetrack with a system like this https://www.amazon.com/Dr-Beat-Racetrack-William-Ziemba/dp/0688072216 https://www.amazon.com/Dr-Beat-Racetrack-William-Ziemba/dp/0... * turn a predictive model for financial prices into a profitable trading system In the case where the bet loses money you can interpret Kelly as either "the only way to win is not to play" or "bet it all on Red exactly once and walk away " depending on how you take the limit.
- kqr 5y agoThat is a much narrower view of the Kelly criterion than the general concept. The general idea is about choosing an action that maximises the expected logarithm of the result. In practise this means, among other things, not choosing an action that gets you close to "ruin", however you choose to measure the result. Another way to phrase it is that the Kelly criterion leads to actions that avoid large losses.
- PaulHoule 5y agoActually https://en.wikipedia.org/wiki/Kelly_criterion https://en.wikipedia.org/wiki/Kelly_criterion "The Kelly bet size is found by maximizing the expected value of the logarithm of wealth, which is equivalent to maximizing the expected geometric growth rate" In real life people often choose to make bets smaller than the Kelley bet. Part of that is that even if you have a good model there are still "unknown unknowns" that will make your model wrong some of the time. Also most people aren't comfortable with the sharp ups and downs and probability of ruin you have with Kelley.
- kqr 5y agoI've long found that Wikipedia article woefully lacking in generality. 1) The Kelly criterion is a general decision rule not limited to bet sizing. Bet sizing is just a special case where you're choosing between actions that correspond to different bet sizes. The Kelly criterion works very well also for other actions, like whether to pursue project A or B, whether to get insurance or not, and indeed whether to sleep under a tree or on a rock. 2) The Kelly criterion is not limited to what people would ordinarily think of as "wealth". It applies just as well to anything you can measure with some sort of utility where compounding makes sense. The best overview I've found so far is The Kelly Capital Growth Investment Criterion[1], which unfortunately is a thick collection of peer-reviewed science, so it's very detailed and heavy on the maths, too. [1]: https://www.amazon.com/KELLY-CAPITAL-GROWTH-INVESTMENT-CRITERION/dp/9814383139/ https://www.amazon.com/KELLY-CAPITAL-GROWTH-INVESTMENT-CRITE...
- deleted 5y ago[deleted]
- Fernicia 5y agoIsn't that called Pascal's Wager?
- wongarsu 5y agoWhich of course directly leads to Pascal's Mugging: I can simply say "I'm a god, give me $10000 or you will burn in hell for all eternity". Now if you follow Pascal's Wager or GP's logic you have to give me the money: I'm probably lying, but the potential downside is too great to risk upsetting me.
- kqr 5y agoThere's actually a rational explanation for that: humans don't care very much about burning in hell for all eternity, when it comes down to it. There's actually a similar though experiment that might seem even more bizarre: I could tell you "give me $100 or I will kill you tomorrow" and you probably wouldn't give me the $100. That's because when it comes down to it, humans don't see the loss of their life as that big a deal as one might think. It's a big deal, of course, but in combination with the low likelihood, still not big enough to forgo the $100.
- dsr_ 5y agoHere's the thing: if you have just killed five people, "give me $100 or I will kill you tomorrow" becomes a much more effective threat. One-time games and repeated games have different strategies.
- kqr 5y agoIt becomes more effective only because it changes the probability estimation of the outcome. Life is a repeated game of decisions that compound on each other, so that difference is irrelevant.
- AlexCoventry 5y agoPascal's Wager is a fallacy resulting from plugging infinity into your risk analysis and interpreting ∞/0 in a way that suits you.
- anter 5y agoIf anyone wants to play around with an interactive explanation of the The Kelly criterion: https://explore.paulbutler.org/bet/ https://explore.paulbutler.org/bet/
- HWR_14 5y ago> the mere act of doing it more often dramatically changes the risk. Kind of. However, you already know that the first N outings didn't have a disaster. So those should be discarded from your analysis. Doing it N times more has a lot of risk, doing it the N+1th time has barely any.
- HPsquared 5y agoThe "slippery slope" principle applies here though: N+1 enables N+2, which enables N+3 and so on.
- aaronblohowiak 5y agobut the risk is independent. so once you do the N+1 time safely, you are back to N and your next time is _also_ just an N+1.
- pessimizer 5y agoContinuing to do something regularly doesn't ever mean you're just going to do it once more.
- nefitty 5y agoPsychologically, behaving in a certain way makes it more likely that you'll behave in the same way in the future. That's an integral idea underpinning justice systems.
- twobitshifter 5y agoTrue but it would be incorrect to assume that you can safely keep basejumping every day in a year, just because you haven’t died in the last 50 days. Eventually the stats say you will be 87% likely to have an accident when you consider your choice at the beginning of the year. It might be day 20 or day 300, but you won’t know what case you end up in. The chance of your next jump being your last is always the same, but that doesn’t decrease the risk of repeated trials.
- JadeNB 5y ago> 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. Indoor climbing, and especially bouldering, can be a lot of fun at the right gym, and with dramatically reduced risk of death (though injury is still a very real possibility, I say, recalling all the time I spent nursing my sprained ankle).
- derbOac 5y ago"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.
- thehappypm 5y agoMountaineers is where I heard it.
- pugets 5y agoThis line is famous in aviation, where X = pilots
- derbOac 5y agoYeah after I read that many years ago I saw it come up in several other contexts (including aviation) and realized it probably originated elsewhere.
- timClicks 5y agoThe risks are highest when learners are at a beginner to intermediate stage. They know the basics, and have gained some confidence, but don't know enough to get themselves out of trouble. This is called Stage 1 in the Gordon Model of learning: unconscious incompetence.
- Breza 5y agoThat reminds me of when a family friend from church needed help clearing his land and thought the easiest approach would be to teach an overconfident 14 year old (me) to drive his tractor. He told me I would never be worse at operating it than the second time we went out. He was right.
- datameta 5y agoAlso known as an advanced beginner, the stage before competency. Someone who has enough knowledge to, as they say, "be dangerous".
- vincentmarle 5y agoThis is called ergodic theory, the more you repeat an action that could result in catastrophe, the likelihood of that catastrophe occuring will be close to 100% if the number of events is high enough.
- epolanski 5y agoBut that doesn't imply any higher probability. Say chance of dying when doing alpinism is one in a thousand. The 1000th time you go climbing the chances of dying are still 1/1000. If you get 100 heads in a row, the 101th time you launch a coin the chance of getting heads is still 50%.
- ska 5y agoRight, but it's easy to conflate two very things here: "What are my chances of dying in a climbing accident", and "What are my chances of dying today if I go climbing". If you are on a plane, you* have a lower risk of some kinds of cancer than the airline staff do. This has nothing to do with the flight you are both on, and everything to do with accumulated flights "you*" = for most people, i.e. barring a counteracting risk factor.
- deleted 5y ago[deleted]
- kenjackson 5y agoThis is exactly why people who do high risk think it will never happen to them.
- segmondy 5y agoI would imagine that if you scale back enough tho, you won't be as sharp. Sure the odds increase the more you do it, but not just because you do it, but often because of other variables, such as the weather, not listening to your body, over confidence, etc.
- yodsanklai 5y agoThat'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, it happens frequently. That being said, if you serious about security, I'm sure the risk can be minimal.
- chimprich 5y agoYou 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-benefits-of-cycling-outweigh-the-risks-by-far/ https://blogs.bmj.com/bjsm/2018/12/12/pedal-power-the-health...
- kenjackson 5y agoLots of ways to get even better cardio benefits with much less risk.
- e40 5y agoSame reason I sold my motorcycle when I was 30. I had a good run of not being maimed, but the odds were not good for the future.
- blunte 5y agoYou would probably be at less risk if you continued rock climbing but eschewed driving (or riding in) a car.
- zmmmmm 5y agoI took the same approach with motorcycling. I decided to do it for 3 years while at university because it had a transformative impact on my lifestyle. But I also decided the odds were way too bad to keep doing it my whole life. So I stopped and haven't done it since then.
- gilbetron 5y agoI only owned a bicycle for several years at the same age, and have since mostly used a car to get around. I've been in various, relatively minor accidents with both, and have always wanted to try using a motorcycle, but it seems to take the risks of both biking and driving and puts them together!
- hgomersall 5y ago"Climb if you will, but remember that courage and strength are nought without prudence, and that a momentary negligence may destroy the happiness of a lifetime. Do nothing in haste; look well to each step; and from the beginning think what may be the end" ~Edward Whymper
- throwaway6532 5y agoThis is why I don't drive or talk to people anymore.