4 ms·

Taleb uses his own definition of ergodicity which he's yet to state

dxbydt 7y ago
I’m curious why you would think that. afaik, Taleb has repeatedly & explicitly stated “no probability without ergodicity”, which is pretty much a frequentist mantra. The problem with non-statisticians like Nate Silvers (who holds a BS in Econ, as opposed to Taleb who earned his PhD in Statistics), is that they traffic in electoral polls involving human subjects which are anything but ergodicity. Yet, they brazenly attribute probability models to their conclusions. That has severe definitional issues, which is what Taleb objects to. As to the gatekeeping issues, my mom buys eggs for $3 and groceries for $7. 3+7=10, so she hands over a $10 bill. Wait a minute, does that mean my mom is a mathematician, because she has engaged in arithmetic, which is math ? That’s the issue here. Silvers can simply post how many people want to vote which way & leave it at that. It’s just an opinion poll. Instead he engages in an elaborate charade where he takes polls of polls, ensemble averages, then says this is what is most likely, then on election day when most likely becomes least likely, he washes his hands off. Thats just clearcut fraud. All Taleb is saying is that you simply don’t have ergodicity here so you don’t have a probability. You just have a [0..1] fraction that doesn’t mean much because it doesn’t converge to a limit as information approaches infinity. So if you had skin in the game and purchased an option based on the projected outcome you would lose big time.
- kgwgk 7y ago
  > as opposed to Taleb who earned his PhD in Statistics Wrong.
  - gowld 7y ago
    Management Science / Nassim Taleb - 1998 : The Microstructure of Dynamic Hedging https://helyettegeman.com/phd-students/ https://helyettegeman.com/phd-students/ Not so different from economics.
- kgwgk 7y ago
  > So if you had skin in the game and purchased an option based on the projected outcome you would lose big time. Would you lose at any odds? Then the probability is zero. Would you (expect to) lose at some odds and win if the odds offered were different? Then the probability is somewhere in between.
- yellowstuff 7y ago
  I don't understand your (or Taleb's) point. If you insist on "no probability without ergodicity" then you can't put a probability on stock price movement, or any election or sporting event. But people put probabilities on those all the time. If that breaks the assumptions of frequentist models then it's the frequentists who are wrong about what people mean when they use probabilities. I agree with the idea that Nate Silver is an entertainer, and if he were a bookie he'd need to be more precise about the odds he places on things and his range of uncertainty. But to me that doesn't suggest that Silver shouldn't speak in terms of probability at all. For a journalist (a big caveat) he's remarkable for being rigorous, open about his level of certainty, and willing to admit to mistakes.
  - patrick5415 7y ago
    I disagree that statisticians should adjust their definitions to fit common usage. I can put any probably on anything I want. That doesn’t imply those numbers mean anything usefu or that what I’m doing is backed by any established theory.
    - kgwgk 7y ago
      There are established theories of probability that have nothing to do with ergodicity. See for example: Laplace - Théorie analytique des probabilités - 1812 Keynes - A Treatise on Probability - 1921 Jeffreys - Theory of Probability - 1939 Savage - The Foundations of Statistics - 1954 de Finetti - Teoria delle Probabilità - 1970
- vbuwivbiu 7y ago
  your reply made me question myself so I got Skin in the Game off the shelf and whadddayknow he _does_ give a definition: "Perfect ergodicity means that each one of us, should he live forever, would spend a proportion of the time in the economic conditions of the entire cross-section[of the U.S. population]: out of, say, a century, an average of sixty years in the lower middle class, twenty years in the blue-collar class, and perhaps one single year in the one percent"
- vladTheInhaler 7y ago
  I hardly think it's fair to say that Nate Silver isn't interested in accountability for his predictions. The site recently finished a retrospective that tries to address this issue: https://projects.fivethirtyeight.com/checking-our-work/ https://projects.fivethirtyeight.com/checking-our-work/ Probability theory, whether frequentist or otherwise, is "just" math. Identifying that mathematical structure with real-world events is always going to involve a judgment call. So if your framework requires assumptions that don't hold in the real world, then maybe it's not the appropriate framework to use. Because clearly people are making decisions based on numbers between 0 and 1, and they're not generally losing big time.

I’m curious why you would think that. afaik, Taleb has repeatedly & explicitly stated “no probability without ergodicity”, which is pretty much a frequentist mantra. The problem with non-statisticians like Nate Silvers (who holds a BS in Econ, as opposed to Taleb who earned his PhD in Statistics), is that they traffic in electoral polls involving human subjects which are anything but ergodicity. Yet, they brazenly attribute probability models to their conclusions. That has severe definitional issues, which is what Taleb objects to. As to the gatekeeping issues, my mom buys eggs for $3 and groceries for $7. 3+7=10, so she hands over a $10 bill. Wait a minute, does that mean my mom is a mathematician, because she has engaged in arithmetic, which is math ? That’s the issue here. Silvers can simply post how many people want to vote which way & leave it at that. It’s just an opinion poll. Instead he engages in an elaborate charade where he takes polls of polls, ensemble averages, then says this is what is most likely, then on election day when most likely becomes least likely, he washes his hands off. Thats just clearcut fraud. All Taleb is saying is that you simply don’t have ergodicity here so you don’t have a probability. You just have a [0..1] fraction that doesn’t mean much because it doesn’t converge to a limit as information approaches infinity. So if you had skin in the game and purchased an option based on the projected outcome you would lose big time.

kgwgk 7y ago
> as opposed to Taleb who earned his PhD in Statistics Wrong.
- gowld 7y ago
  Management Science / Nassim Taleb - 1998 : The Microstructure of Dynamic Hedging https://helyettegeman.com/phd-students/ https://helyettegeman.com/phd-students/ Not so different from economics.
kgwgk 7y ago
> So if you had skin in the game and purchased an option based on the projected outcome you would lose big time. Would you lose at any odds? Then the probability is zero. Would you (expect to) lose at some odds and win if the odds offered were different? Then the probability is somewhere in between.
yellowstuff 7y ago
I don't understand your (or Taleb's) point. If you insist on "no probability without ergodicity" then you can't put a probability on stock price movement, or any election or sporting event. But people put probabilities on those all the time. If that breaks the assumptions of frequentist models then it's the frequentists who are wrong about what people mean when they use probabilities. I agree with the idea that Nate Silver is an entertainer, and if he were a bookie he'd need to be more precise about the odds he places on things and his range of uncertainty. But to me that doesn't suggest that Silver shouldn't speak in terms of probability at all. For a journalist (a big caveat) he's remarkable for being rigorous, open about his level of certainty, and willing to admit to mistakes.
- patrick5415 7y ago
  I disagree that statisticians should adjust their definitions to fit common usage. I can put any probably on anything I want. That doesn’t imply those numbers mean anything usefu or that what I’m doing is backed by any established theory.
  - kgwgk 7y ago
    There are established theories of probability that have nothing to do with ergodicity. See for example: Laplace - Théorie analytique des probabilités - 1812 Keynes - A Treatise on Probability - 1921 Jeffreys - Theory of Probability - 1939 Savage - The Foundations of Statistics - 1954 de Finetti - Teoria delle Probabilità - 1970
vbuwivbiu 7y ago
your reply made me question myself so I got Skin in the Game off the shelf and whadddayknow he _does_ give a definition: "Perfect ergodicity means that each one of us, should he live forever, would spend a proportion of the time in the economic conditions of the entire cross-section[of the U.S. population]: out of, say, a century, an average of sixty years in the lower middle class, twenty years in the blue-collar class, and perhaps one single year in the one percent"
vladTheInhaler 7y ago
I hardly think it's fair to say that Nate Silver isn't interested in accountability for his predictions. The site recently finished a retrospective that tries to address this issue: https://projects.fivethirtyeight.com/checking-our-work/ https://projects.fivethirtyeight.com/checking-our-work/ Probability theory, whether frequentist or otherwise, is "just" math. Identifying that mathematical structure with real-world events is always going to involve a judgment call. So if your framework requires assumptions that don't hold in the real world, then maybe it's not the appropriate framework to use. Because clearly people are making decisions based on numbers between 0 and 1, and they're not generally losing big time.