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Live betting from Betfair's betting exchange / prediction market: https://www.betfair.com/exchange/plus/#/politics/market/1.118739911 https://www.betfair.com/e

Live betting from Betfair's betting exchange / prediction market: https://www.betfair.com/exchange/plus/#/politics/market/1.118739911 https://www.betfair.com/exchange/plus/#/politics/market/1.11... Interesting because the odds react far quicker than any live blog I've found, so a sudden swing means that there's just been a surprising result announced.

bbcbasic 10y ago
Given that there will be a number of swings maybe a good strategy is to bet on the one with longer odds, wait till the next swing, sell and buy the other, rinse and repeat. Profit!
- joosters 10y ago
  Odds on 'remain' have already oscillated in the last few hours from 1/16 to 2/1 (94% to 33% implied probability)
  - bbcbasic 10y ago
    I saw that reverse for a few minutes on Betfair. It's a fairly illiquid market looking at the depths.
    - joosters 10y ago
      About £100 million has the traded on that market, that's far from illiquid.
jsprogrammer 10y ago
Or, someone made a large transaction.
- jessaustin 10y ago
  More likely that many people made bets, which they'll do when, as parent had it, "there's just been a surprising result announced."
dzdt 10y ago
What is the formula to translate from betfair's back/lay for exit/remain to percent likelihood of each outcome?
- selectron 10y ago
  This site does the calculation: https://electionbettingodds.com/brexit.html https://electionbettingodds.com/brexit.html
- danielvf 10y ago
  You can go to the graph on betfair and "invert axis" to see the actual probability.
- joosters 10y ago
  Implied probability is 100 / odds
  - BurningFrog 10y ago
    If the odds are 4:1, I'm not sure what that means. 100/4:1 is a notation mystery. 25%?
    - danbruc 10y ago
      x:y or x/y means y / (x + y), so 4:1 is 1 / (4 + 1) or 20 %.
      - dzdt 10y ago
        But what do "back" and "lay" mean?
        danbruc 10y ago
        Back means you bet on something happening, lay means you bet against it happening.
        10y ago
AReallyGoodName 10y ago
Now well over 4:1 for remain. The change in betting ods is extremely interesting from a statistical modelling point of view. http://www.oddschecker.com/politics/british-politics/eu-referendum/referendum-on-eu-membership-result http://www.oddschecker.com/politics/british-politics/eu-refe... I don't care about the result. I'm more interested in how our statistical modelling tools failed us. Thoughts? Did opinions change overnight? Did the polling miss a demographic?
- fdsaaf 10y ago
  Bradley effect: https://en.wikipedia.org/wiki/Bradley_effect https://en.wikipedia.org/wiki/Bradley_effect (Also known as social desirability bias) Lots of people say in public that they're in favor of immigration, unity, and tolerance, because lots of people will call you a bigot if you don't, but in private, harbor old-fashioned ideas about nationalism, and well, polling involves a human and voting happens in private.
  - evanpw 10y ago
    But if this is a known effect, why were the betting markets also wrong?
    - fdsaaf 10y ago
      I think betting markets are prone to wishful thinking; there's no guarantee that errors of reasoning toward one side or the other will cancel out, since it's perfectly reasonable to imagine that errors in one direction are more common.
      - maxerickson 10y ago
        There's no guarantee, but the bookie is watching his, uh, book and adjusting the odds to make sure the payouts come from losing bets rather than his pocket.
        10y ago
fefifofu 10y ago
The foreign exchange market has more volume and eyes watching it. Just watch the value of the GBP.

bbcbasic 10y ago

Given that there will be a number of swings maybe a good strategy is to bet on the one with longer odds, wait till the next swing, sell and buy the other, rinse and repeat. Profit!

joosters 10y ago
Odds on 'remain' have already oscillated in the last few hours from 1/16 to 2/1 (94% to 33% implied probability)
- bbcbasic 10y ago
  I saw that reverse for a few minutes on Betfair. It's a fairly illiquid market looking at the depths.
  - joosters 10y ago
    About £100 million has the traded on that market, that's far from illiquid.

jsprogrammer 10y ago

Or, someone made a large transaction.

jessaustin 10y ago
More likely that many people made bets, which they'll do when, as parent had it, "there's just been a surprising result announced."

dzdt 10y ago

What is the formula to translate from betfair's back/lay for exit/remain to percent likelihood of each outcome?

selectron 10y ago
This site does the calculation: https://electionbettingodds.com/brexit.html https://electionbettingodds.com/brexit.html
danielvf 10y ago
You can go to the graph on betfair and "invert axis" to see the actual probability.
joosters 10y ago
Implied probability is 100 / odds
- BurningFrog 10y ago
  If the odds are 4:1, I'm not sure what that means. 100/4:1 is a notation mystery. 25%?
  - danbruc 10y ago
    x:y or x/y means y / (x + y), so 4:1 is 1 / (4 + 1) or 20 %.
    - dzdt 10y ago
      But what do "back" and "lay" mean?
      - danbruc 10y ago
        Back means you bet on something happening, lay means you bet against it happening.
      - 10y ago

AReallyGoodName 10y ago

Now well over 4:1 for remain. The change in betting ods is extremely interesting from a statistical modelling point of view. http://www.oddschecker.com/politics/british-politics/eu-referendum/referendum-on-eu-membership-result http://www.oddschecker.com/politics/british-politics/eu-refe... I don't care about the result. I'm more interested in how our statistical modelling tools failed us. Thoughts? Did opinions change overnight? Did the polling miss a demographic?

fdsaaf 10y ago
Bradley effect: https://en.wikipedia.org/wiki/Bradley_effect https://en.wikipedia.org/wiki/Bradley_effect (Also known as social desirability bias) Lots of people say in public that they're in favor of immigration, unity, and tolerance, because lots of people will call you a bigot if you don't, but in private, harbor old-fashioned ideas about nationalism, and well, polling involves a human and voting happens in private.
- evanpw 10y ago
  But if this is a known effect, why were the betting markets also wrong?
  - fdsaaf 10y ago
    I think betting markets are prone to wishful thinking; there's no guarantee that errors of reasoning toward one side or the other will cancel out, since it's perfectly reasonable to imagine that errors in one direction are more common.
    - maxerickson 10y ago
      There's no guarantee, but the bookie is watching his, uh, book and adjusting the odds to make sure the payouts come from losing bets rather than his pocket.
      - 10y ago

fefifofu 10y ago

The foreign exchange market has more volume and eyes watching it. Just watch the value of the GBP.