5 ms·
> even if the chance of survival for a medical operation is either 10% or 90%, the practical chance the patient is battling is always 50% because he either live
by jefftk 3y ago
> even if the chance of survival for a medical operation is either 10% or 90%, the practical chance the patient is battling is always 50% because he either lives or dies from that operation
I think this is rarely a productive way to think about it. For example, the chance that I might die in the next year is somewhere between 0% and 100%, and actuarial tables put it somewhere around 0.3%. [1] Should I refrain from having a kid because I'd have a "50% chance" of leaving them without a dad before they turned 1?
[1] https://www.ssa.gov/oact/STATS/table4c6.html https://www.ssa.gov/oact/STATS/table4c6.html
- ant6n 3y agoWell, using this logic, every day you have a 50% chance of dying, since you either die or you don't. Or perhaps every second you have a 50% chance of dying. ...obviously this "math" doesn't quite work out.
- jefftk 3y agoI mean, it clearly doesn't work if taken to be literal probabilities. But I think it also doesn't work as a more metaphorical guide to life?
- kergonath 3y agoIt clearly does not work in any circumstances. We over-emphasise the likelihood of rare events already, saying that something has even odds just because it is conceivable that it could happen is completely useless. Which is not to say that you should not plan for extremely rare events, but you certainly should not make decisions assuming they are likely to happen.
- snapcaster 3y agoI think you're maybe missing the point. My understanding would be something like: My chances of being killed by a shark is basically 0%. But, if I'm in a shark cage surrounded by sharks the idea that some global probability is 0% isn't relevant. Something like that?
- jefftk 3y agoIf I'm in a shark cage then the probability that matters is conditional on being in a shark cage, sure. And it should certainly be higher than the global probability. But I don't see how this connects to saying that anything that can go two ways is 50-50? ("always 50% because he either lives or dies from that operation")
- snapcaster 3y agoI think the 50% part should be ignored and the message is "when dealing with an individual sample, the general probability distribution isn't that useful?" I don't actually agree with that, just trying to steel man the point a bit. I do kind of see what he means
- vel0city 3y agoThere's also a 50/50 chance a world ending meteor hits in the next minute. But don't worry, there's a 50/50 chance you'll win the lottery tonight.