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Eric1969 t1_izt3tqu wrote

Reply to comment by Mooks79 in Football betting experiment: what if I consistently bet against the odds, on the least likely match outcome? This is the English Premier League. What happened in 2019/20? (sorry for the third similar post, I test different competitions incrementally after the jaw-dropping World Cups' results) [OC] by ikashnitsky

My friend’s theory was that lagging outcomes (ex: tails having come up 20 times for 40 heads) would result in these outcomes having a higher probability than the theoretical probability (50% for heads and tails) of showing up, as they would surely eventually catch up. I tought the probability remained 50% regardless.

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Mooks79 t1_izt3zcr wrote

I’m with you. I think if your friend’s code showed otherwise then there’s a flaw in the code and it’s not doing quite what it should be. Would they be willing to share it?

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Eric1969 t1_izt69qy wrote

It was 30 years ago in visual basic. So I don’t have access to it.

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Mooks79 t1_izt6qzt wrote

Ah! If I were you I would stick with your original thinking as I’m reasonably confident there was a coding issue or the set-up of the simulation wasn’t quite what it should be. If I have time I might try and knock something together myself, but that’s a big if as I’ve got a mental couple of weeks.

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Eric1969 t1_izt83c8 wrote

I agree. Also, the random numbers produced by a computer are “pseudo-random”.

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Mooks79 t1_izt8d0z wrote

They should be random enough, albeit improperly generated random numbers could be a cause. My money is on them setting up the simulation incorrectly, though. When I say incorrectly, I mean it could be that they haven’t set the simulation up quite as they think they have.

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Mooks79 t1_j1dtis7 wrote

Finally got round to knocking up a simulation, can confirm that the two methods (randomly choosing whether to bet H or T, or using the lagged counts) both give the same (0.5) win rate, as expected. Indeed, any strategy (e.g. always choosing H or T) will yield the same win rate for a truly random coin. I suspect there was a slight glitch in your friend’s simulation. Happy to share (R) code and plot(s) if you want.

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