saturn comments on Why We Can't Take Expected Value Estimates Literally (Even When They're Unbiased) - Less Wrong

75 Post author: HoldenKarnofsky 18 August 2011 11:34PM

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Comment author: saturn 18 August 2011 08:21:16PM 5 points [-]

This is the frequentist answer to the same question. Cue standard bayesian vs. frequentist debate.

Of course, you're right that BeerAdvocate could get more accurate rankings with a more fine-tuned prior, but other than that I don't see what's wrong with their method.

Comment author: RobinZ 31 August 2011 10:47:46PM 1 point [-]

I think the "basically a hack" argument isn't entirely without merit in this case, bayesian or frequentist - from what is said in the article, BeerAdvocate chose m without a lot of attention to:

  • frequentist hat: the relative rate of Type I and Type II errors.

  • Bayesian hat: the relative probability of a rating increasing versus decreasing with the addition of more reviews.

Comment author: novalis 18 August 2011 08:34:00PM -1 points [-]

Well, that's just the entire point of this LW post -- what prior to choose matters a lot. It even matters specifically in the case of BeerAdvocate, who apparently got appreciably different results from changing their value of 10 reviews.

Comment author: saturn 18 August 2011 08:42:22PM *  3 points [-]

And the solution you suggest is to just go with p=0.05 and pretend this problem isn't unavoidable, right?

Comment author: novalis 18 August 2011 09:26:19PM 1 point [-]

I think I specifically said that variance matters. I'll also say that your application matters -- when choosing beers, I would be OK with p much worse than 0.05 since I can afford to order another beer. When choosing charities, it is a harder question.