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Bayes's Theorem: What's the Big Deal?

blogs.scientificamerican.com

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Re: Bayes's Theorem: What's the Big Deal?

#61

Post by cwyers »

vezzy-fnord wrote: post #27
cwyers wrote: post #5

> In many cases, estimating the prior is just guesswork, allowing subjective factors to creep into your calculations. You might be guessing the probability of something that--unlike cancer—does not even exist, such as strings, multiverses, inflation or God. You might then cite dubious evidence to support your dubious belief. In this way, Bayes’ theorem can promote pseudoscience and superstition as well as reason. Oh…

Yudkowsky has been one of the most instrumental and highly regarded figures in promoting Bayesian epistemology, among other woo that engineers and programmers are oddly susceptible to. Nothing wrong with singling him out.

I agree with pretty much everything you say here, but then I think the article conflates Yudkowsky's Bayes-flavored woo with what most people mean when they talk about Bayesian statistics.

Re: Bayes's Theorem: What's the Big Deal?

#62

Post by TeMPOraL »

RodericDay wrote: post #57
TeMPOraL wrote: post #45

Earlier quoted context omitted.

I've seen this type of writing before. It's a kind of twisted pseudo-criticism you write against a group you dislike. You can compose stuff like this against any group. It sounds believable from the outside, especially if you start sceptical to begin with. But take a closer look - it's actually full of ad-hominems, cherry-picking facts and presenting them in worst light possible. I've been a part of several groups th…

I know you're a huge advocate for Lesswrong, but not "everybody" or "anyone" has quotes ripe for picking like Yudkowsky. Stephen Bond is not just throwing some opinion out there, he's backing it up with first-hand sources: Yudkowsky on his simplified views of why race gets brought up: > "Race adds extra controversy to everything; in that sense, it's obvious what difference skin colour makes politically". > "Group inj…

I'm not that huge advocate of LW. I used to frequent the site, I read the Sequences and generally liked what I saw.

RE parts you quoted. Of course they look bad, because they've been ripped out from context.

Race:

http://lesswrong.com/lw/kk/why_are_individual_iq_differences...

This is an article asking, to quote: "But why is it that the rest of the world seems to think that individual genetic differences are okay, whereas racial genetic differences in intelligence are not?". Yudkowsky seems to argue that making big controversies around whether there are, or are not, differences between "races" is missing the point; it's just one of many variables and we should focus on fixing intelligence disparities for everyone.

Society:

http://lesswrong.com/lw/ub/competent_elites/

This blogpost is marked as controversial from the get-go. It covers a quite interesting theory IMO - that the very common meme, which says that elites are stupid and evil, is in fact wrong. Eliezer argues towards a more socially uncomfortable opinion - that elites are, in fact, smarter and better at organizing things. Given that this is a belief most people are heavily biased against, it actually may be the "thing you can't say", per PG's essay at http://www.paulgraham.com/say.html.

Story:

Geez. This is a sci-fi story. Moreover, it's explicitly designed to fuck with reader's moral intuitions. That's its entire point. Personally, I find it fun and insightful, but it is heavy. You can read the whole work here:

http://lesswrong.com/lw/y4/three_worlds_collide_08/

--

And to be clear. I'm not idolizing Eliezer. He's just a man who thought a lot about some stuff, and wanted to share it. He sometimes gets it wrong (and, as opposed to many, has at least the courage to admit he was wrong). But I absolutely hate this kind of bullshit pseudocriticism when it's directed against anyone - be it my friend or enemy, be it someone I admire or despise of. Eliezer is not beyond criticism, but we can do better than that.

Re: Bayes's Theorem: What's the Big Deal?

#63

Post by jimrandomh »

RodericDay wrote: post #57
TeMPOraL wrote: post #45

Earlier quoted context omitted.

I've seen this type of writing before. It's a kind of twisted pseudo-criticism you write against a group you dislike. You can compose stuff like this against any group. It sounds believable from the outside, especially if you start sceptical to begin with. But take a closer look - it's actually full of ad-hominems, cherry-picking facts and presenting them in worst light possible. I've been a part of several groups th…

I know you're a huge advocate for Lesswrong, but not "everybody" or "anyone" has quotes ripe for picking like Yudkowsky. Stephen Bond is not just throwing some opinion out there, he's backing it up with first-hand sources: Yudkowsky on his simplified views of why race gets brought up: > "Race adds extra controversy to everything; in that sense, it's obvious what difference skin colour makes politically". > "Group inj…

These sorts of quotes can reveal a lot about the source that quoted them, if you track them back to their original source and check for reasonableness there. I think you'll find that each of these quotes had its meaning or connotation dramatically altered by the removal of context.

Re: Bayes's Theorem: What's the Big Deal?

#64

Post by cwyers »

privong wrote: post #6
cwyers wrote: post #5

> In many cases, estimating the prior is just guesswork, allowing subjective factors to creep into your calculations. You might be guessing the probability of something that--unlike cancer—does not even exist, such as strings, multiverses, inflation or God. You might then cite dubious evidence to support your dubious belief. In this way, Bayes’ theorem can promote pseudoscience and superstition as well as reason. Oh…

> Oh please. You can do plenty of psuedoscience and superstition with good old frequentist statistics. That's not really the point. The article is simply saying that Bayesian methods are not a silver bullet; it's not saying that other methods of statistics are free from problems.

> The article is simply saying that Bayesian methods are not a silver bullet

But it's not really saying it in passing; the headline is taken from that paragraph. At that point it almost feels like a takedown of a strawman Bayesian.

Re: Bayes's Theorem: What's the Big Deal?

#65

Post by Fomite »

skybrian wrote: post #56
Fomite wrote: post #42

Earlier quoted context omitted.

In my field (Epidemiology), when doing Bayesian analysis, it is very common to set one's priors to be a distribution. Sometimes the point estimate and spread of a previously conducted study or meta-analysis, sometimes merely a uniform distribution with upper and lower bounds ("It is extremely unlikely that the relative risk of disease for this exposure is below 0.01 or above 100...") It's been argued that frequentist…

How does that work? It doesn't sound like a well-defined distribution since the area under the curve needs to be 1.

It's more of a philosophical statement than an actual implementation. Mainly that frequentist analysis begins with the prior "I dunno, could be anything..."

See also: The calculus answer.

Re: Bayes's Theorem: What's the Big Deal?

#66

Post by TeMPOraL »

zepto wrote: post #59
TeMPOraL wrote: post #38

Earlier quoted context omitted.

Yup. Actually, a common theme on LessWrong was realizing that with better reasoning tools you're more able to bullshit yourself , and so you need to be extra-careful.

How do you be extra careful except by developing yet more powerful reasoning tools?

You can't protect yourself in 100% - it would require developing more powerful reasoning tools in an infinite regression. But what you can do is to use introspection, and triple-check your reasoning when it seems to defy common sense or leads you to weird (awful) conclusions.

That's why LW is so big on biases and heuristics by the way - you can treat them as a list of warning signs; if your reasoning seems to match some of them, it's time to take a closer look.

(A thing a lot of people missed since knowing logical fallacies started to become a mainstream thing - you should use the list to check your own reasoning, not your opponent's.)

Re: Bayes's Theorem: What's the Big Deal?

#67

Post by Jabbles »

Anderkent wrote: post #50
hyperpape wrote: post #44

Earlier quoted context omitted.

I'm not quite sure what you're saying. Doctors don't observe probabilities or enormous frequencies. Either way, there are good odds that this is information that someone is communicating to them, not the result of their personal experience.

Doctors observe a result of the test, and know the basic probabilities (in the example, 99% test accuracy, 1% of population have the disease). The problem is that they [often] draw incorrect conclusions from those observations (99% test accuracy and you tested positive? well then you likely - 99% - have the disease, right?). The question formed as 'your one patient tested positively' is more immediately relevant, I'd…

Of course, doctors do not randomly assign tests to patients. Their prior that a patient has a disease is a lot higher than the background frequency of it occurring.

Getting them to estimate their prior would be interesting.

Re: Bayes's Theorem: What's the Big Deal?

#68

Post by crpatino »

stuartaxelowen wrote: post #4

Read through most of the article just for "people can abuse priors"? Come on. Anything, used wrongly, can promote superstition and pseudoscience.

On the other hand, one could argue that whenever the Church of Scientism sees someone using one of their favorite tools to argue in favor or a subject considered taboo, said church declares the use of said tool to be "invalid" or "out of scope".

Re: Bayes's Theorem: What's the Big Deal?

#69

Post by [deleted] »

GavinB wrote: post #12

This headline does not reflect the article and is needlessly inflammatory. This article is an explanation of Bayes theorem and overall very positive of it. The "used wrongly" quote is just stating that it's not immune to biases and error. Pretty much any tool "used wrongly" can cause errors. (In case it's changed, the headline currently reads "Bayes theorem used wrongly, can promote superstition and pseudoscience")

[deleted]

Re: Bayes's Theorem: What's the Big Deal?

#70

Post by bmh100 »

skybrian wrote: post #56
Fomite wrote: post #42

Earlier quoted context omitted.

In my field (Epidemiology), when doing Bayesian analysis, it is very common to set one's priors to be a distribution. Sometimes the point estimate and spread of a previously conducted study or meta-analysis, sometimes merely a uniform distribution with upper and lower bounds ("It is extremely unlikely that the relative risk of disease for this exposure is below 0.01 or above 100...") It's been argued that frequentist…

How does that work? It doesn't sound like a well-defined distribution since the area under the curve needs to be 1.

It has to do with calculus. If the probability of a given result approaches zero as the result itself approaches positive or negative infinity, then the area under the curve approaches 1.

Imagine 1/2 + 1/4 + 1/8 ... to infinity. The sum approaches 1 as the denominator approaches infinity. With calculus, we can determine that with mathematical methods.

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