All of gerg's Comments + Replies

3jimrandomh
The Alice/Bob naming convention has nothing to do with rank; they're alphabetical by order of first mention. I believe the convention started in contexts where the author is likely to start with prose and switch into math with single-letter names A and B.
gerg50

Second, I don't believe you. I say it's always smarter to use the partitioned data than the aggregate data. If you have a data set that includes the gender of the subject, you're always better off building two models (one for each gender) instead of one big model. Why throw away information?

If you believe the OP's assertion

Similarly, for just about any given set of data, you can find some partition which reverses the apparent correlation

then it is demonstrably false that your strategy always improves matters. Why do you believe that your strategy is better?

2Daniel_Burfoot
Partitioning may reverse the correlation or it may not; either way, it provides a more accurate model. Let's do this formally. Let R, G, and T be the three variables of interest in the OP's example, corresponding to Recovery, Gender, and Treatment. Then the goal is to obtain a model of the probability of R, given T and maybe G. My assertion is that a model of the form P(R|G,T) is always going to be more accurate than a model of the form P(R|T) alone - you can't gain anything by throwing away the G variable. The accuracy can be measured in terms of the log-likelihood of the data given the model. It is actually tautologically true that P(R|G,T) will provide a higher log-likelihood than P(R|T). The issue raised by RobinZ is that P(R|G,T) might overfit the data: the accuracy improvement achieved by including G might not justify the increase in model complexity. That will certainly happen if naive modeling methods are used, but there are ways to incorporate multiple information sources without overfitting.
gerg00

Ha - that post refers to Diax's Rake, which is what happened to spur me to find the Thucydides quote in the first place!

In other news, I've invented this incredible device I call a "wheel".

gerg160

It is a habit of mankind to entrust to careless hope what they long for, and to use sovereign reason to thrust aside what they do not desire.

-- Thucydides

7gwern
If I may, I prefer the fuller version: Also, dupe: http://lesswrong.com/lw/2ev/rationality_quotes_july_2010/28gb?c=1
gerg00

Interesting nuance. You have taken "loses" to mean "defeated", presumably leading to "and therefore updated"; I agree that this is by no means an automatic process. But I took "loses" to mean "is less accurate" (which of course makes my interpretation more tautological).

gerg50

My first reading of this quote was essentially "the map loses to the terrain". I interpreted "theory" as "our beliefs" and "practice" as "reality".

1Peter_de_Blanc
If your beliefs are defeated whenever they clash with reality, then you have attained a mastery of rationality that very few humans achieve. Torvalds' quote looks to me like an "is" statement rather than an "ought" statement, so I can't agree with your interpretation.
gerg00

Possibly, yes; but reading a discussion about a topic I don't know anything about is hard, so I'm less likely to get anything out of it, despite the fact that it is there in what you wrote. I'm claiming that the additional "distracting" material would actually serve as a hook to get the reader interested in putting effort into understanding the point of the post.

0Relsqui
Yeah, I can see that. In this particular case it wouldn't have been true for me, but in others it might have been, and I believe that it is for you here.
gerg00

This post, which concentrated on people's commentary about a field of inquiry, could have been improved by including some summary of the field being commented on.

2PhilGoetz
From past experience, I'm pretty sure that would have led to people ignoring the intent of the post, and instead having flamewars over the content of the summary.
1Relsqui
I see what you mean, but I think that would have distracted from the point of the post, which had nothing to do with the fields being used as examples.
gerg10

I'd need to read it again, with pen and paper, to gain an understanding of why the Student-t distribution is the right thing to compute. At the very least I can say this: the probability of one's vote tilting the election is certainly higher in very close elections (as measured beforehand by polls, say) than in an election such as Obama-McCain 2008. The article you quoted suggests the difference in probabilities is much higher than I anticipated. (Unless my calculation, which models the closest possible election, is incorrect.)

Edited to add: Okay, I've inc... (read more)

gerg00

Jane estimates the probability of her vote tilting the presidential election at 1 in 1,000,000; Eric estimates the probability of his vote tilting the presidential election at 1 in 100,000,000. I find both of these estimates orders of magnitude too low.

Eric presumably is modeling the election by saying that with 100,000,000 voters (besides himself), there are 100,000,001 outcomes of their votes, only one of which is a tie which his vote will break. But his conclusion that the odds of deciding the election are about 1 in 100,000,000 assumes that all of thes... (read more)

Wei Dai100

What is the probability your vote will make a difference? seems to be the state-of-the-art in the "deciding vote" type of reasoning. It concludes "On average, a voter in America had a 1 in 60 million chance of being decisive in the presidential election."

gerg00

Don't worry: I don't know the rules of Go; I went to the site linked; and I could only find a link to a link to a video tutorial, not a list of rules, so I stopped trying.

1TobyBartels
Well, that's a shame. Read these or these if you're interested, but only after reading the OP, of course!
gerg30

A presentation critique: psychologically, we tend to compare the relative areas of shapes. Your ovals in Figure 1 are scaled so that their linear dimensions (width, for example) are in the ratio 2:5:3; however, what we see are ovals whose areas are in ratio 4:25:9, which isn't what you're trying to convey. I think this happens for later shapes as well, although I didn't check them all.

3Oscar_Cunningham
Really? I'd have said the exact opposite. For example in this post, the phrase "half the original's size" means that the linear dimensions are halved. This issue also come up in the production of bubble charts, where the size of a circle represents some value. When I look at a bubble chart it is often unclear whether the data is intended to be represented by the area or the radius. It is certainly easier for me to compare linear dimensions than areas.
gerg30

If my estimate is 1000, and someone else's is 300, that's too big a discrepancy to explain by minor variations. It casts doubt on the assumption of identical thermometers. Assuming that I only have the other people's estimates, and there's no opportunity for discussion, I'll search for reasons why we might have come up with completely different answers, but if I find no error in my own, I'll discard all such outliers.

What if everyone else's estimate is between 280 and 320? Do you discard your own estimate if it's an outlier? Does the answer depend on whether you can find an error in your reasoning?

5Richard_Kennaway
Maybe I've made an error no-one else made. Maybe everyone else made an error I didn't make. (I have personally experienced this. I knew what error everyone else was making and stuck to my answer, which in the end turned out to be right.) The thing to do is to find out why the discrepancy happened; then I will know what to do about it. In some situations this will not be possible. Then I will have to just make an optimal Bayesian calculation based on limited information, i.e. guess. But "optimal" no more implies "accurate" than "statistically significant" implies "important".
gerg20

I'm mathematically interested in this procedure; can you please provide a reference?

0jimrandomh
I don't have a reference because the procedure is not rigorous; I came up with it off the top of my head. The intuition is that each of the contestants would've estimated the linear density of the jelly-beans, which is the same on all axes, and then cubed it, so you invert that by taking the cube root to get their actual estimates. To make this rigorous, you'd also have to account for the fact that the jar isn't actually a cube, which I have not done. I'd start by reducing the volume calculation to a bounding box (a cuboid) and a constant multiplicative factor, and assuming that everyone knows the correct constant factor for a cylinder. The length being different between the three dimensions does make a difference. I suspect (but have not proven) that having the jar, say, twice as tall as its diameter, would cause my procedure to act as though the error distribution for the height was twice as large. If anyone knows of a source that handles this class of problem rigorously, please do post it. If not, perhaps it'd make a good exercise for someone looking for topics to write papers on.
gerg20

good thing I didn't go with the username "this.is.she"!

9GloriaSidorum
Orthography is not intuitive. To test my native speaker instinct, I'll pick a case that is. Imagine a user whose name was "Praise_Him". To me, it would be more natural to say "Praise_Him's post" than "Praise_His post"; the former might give me a second's pause, but the latter would make me reread the sentence. Thus, at least the way I use the language, a proper name which incorporates a pronoun is possessivized as a whole, and cousin_it's is correct. But "Its" and "It's" are homophonous, so it wouldn't matter to me much.
4Alicorn
Now I'm going to be arguing about that with myself all day. How do you possessivize a proper noun that ends in the word "it"?
gerg40

Nominating adversarial legal systems as role models of rational groups, knowing how well they function in practice, seems a bit misplaced.

3Hook
Adversarial legal systems were not necessarily designed to be role models of rational groups. They are more like a way to give opposing biased adversaries an incrementally fairer way of fighting it out than existed previously. I'm guessing scientific institutions don't do this because the people involved feel they are less biased (and probably actually are) than participants in a legal system.
0wnoise
But are they better than inquisitorial legal systems?
gerg70

Part of the output of your quizzes is a line of the form "Your chance of being well calibrated, relative to the null hypothesis, is 50.445538580926 percent." How is this number computed?

I chose "25% confident" for 25 questions and got 6 of them (24%) right. That seems like a pretty good calibration ... but 50.44% chance of being well calibrated relative to null doesn't seem that good. Does that sentence mean that an observer, given my test results, would assign a 50.44% probability to my being well calibrated and a 49.56% probability to my not being well calibrated? (or to my randomly choosing answers?) Or something else?

5skepsci
It's also completely ridiculous, with a sample size of ~10 questions, to give the success rate and probability of being well calibrated as percentages with 12 decimals. Since the uncertainty in such a small sample is on the order of several percent, just round to the nearest percentage.
gerg160

Taskifaction doesn't destroy romance any more than it destroys music or dance.

This one sentence alone is worth my upvote for its sheer truth. (Although

Sucking at stuff is not sublime.

is a close second.)

5[anonymous]
I don't agree. I think that it does ruin some of the magic but, if you suck at it, slightly ruined magic is better than no magic. That's speaking from the perspective of someone who's spent a decent amount of time developing/thinking about these things - after sucking at them. There's plenty of practical advice out there. It doesn't really seem appropriate for a less wrong forum but i'd be happy to point people in the direction of some resources if they message me. In fact, I'd be pretty interested in talking to anyone who's interested in the combination of rationality/game in general.
gerg90

Poor kids had ghetto clothes first; rich kids had the clothes second, but ghetto fashion first.