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Lotto: Statistics question

But that doesn't address the issue of them winning less money than they would have, had the generator been random.

The rules probably already limit damages to the price of the ticket so I did address the issue by saying they should get their money back and void the ticket.

Have you got any links to what the actual problem was? I'm having a hard time conceiving how the Lucky Pick machine could have accidently skewed the probabilities for just 1-9 lower than the other numbers. And how much of difference are we talking about? Are there statistics available for how often each number is picked by Lucky Pick and for regular players?
 
If your calculations are correct, then you will get a lower chance of winning, if the picker is biased.

I specifically ran the increasing-numbers simulations to forstall you from saying that. No, the biased picker does not have a lower chance of winning; all of the "win percentage" quantities are asymptotically approaching 1/6, and scattering around it with a Gaussian error of 1/sqrt(n).

Hang on a minute, I'll post a few more decades of the sim when they're finished running.
 
The thing is they got a random number selection for them, it was just a slightly biased random number selection that had no change in their odds of winning.

If I you win when two dice I roll match, as long as one of the dice is fair the odds of a match will always be 1/6. So having one unfair die in this situation does not seem like something you can really take issue with.

Yes yes, I completely concur with the fact that their chances of winning were not affected. The only thing that affects that is the ball picker.

What I am talking about is what people think they are buying. And what they think they are buying (a totally random selection) is not what they bought (a slightly biased selection). Given that lottery marketing sets out to exploit superstition and poor understanding of probability, I think it's perfectly reasonable for people who bought their tickets that way to feel disgruntled.

Lotteries are all about emotions, feelings, irrationality. I would be willing to bet that many lottery players don't understand that sequential numbers have the same chance of winning as any other set, for example. And lotteries pander to and exploit these sorts of irrationalities. For example, the UK lottery slogan 'it could be you' is almost a lie. It almost certainly will not be you. It could be, but I'd be willing to bet £500 it won't be. It will probably be someone. But not you.
 
You are not getting it. It isn't a case of the numbers 1-9 never coming out. It's a case of the numbers 1-9 coming out less often than the rest.

I specifically stated this several times.

And what you are missing is that it does not matter. The only effect is that there might have been more or less people winning particular pots.

The odds of a specific ticket winning does not matter how biased the ticket is.
 
And what you are missing is that it does not matter. The only effect is that there might have been more or less people winning particular pots.

The odds of a specific ticket winning does not matter how biased the ticket is.

And I would think (but haven't done any calculations) that it would barely effect the actual winnings, either - at least of the bigger prices. The difference would be much more drastic for small prices (percentage wise).
 
Yes yes, I completely concur with the fact that their chances of winning were not affected. The only thing that affects that is the ball picker.

What I am talking about is what people think they are buying. And what they think they are buying (a totally random selection) is not what they bought (a slightly biased selection). Given that lottery marketing sets out to exploit superstition and poor understanding of probability, I think it's perfectly reasonable for people who bought their tickets that way to feel disgruntled.

It was random. It was just a slightly biased random. The thing is that I am not sure how many lottery players understand the difference or lack there of. If they had a good understanding of statistics they would likely not be playing the lottery now would they?
Lotteries are all about emotions, feelings, irrationality. I would be willing to bet that many lottery players don't understand that sequential numbers have the same chance of winning as any other set, for example. And lotteries pander to and exploit these sorts of irrationalities. For example, the UK lottery slogan 'it could be you' is almost a lie. It almost certainly will not be you. It could be, but I'd be willing to bet £500 it won't be. It will probably be someone. But not you.

Ah but you have the same odds as anyone else. So the thing is that as they individuals have a poor understanding of statistics, why do you think that this is something that should be treated as a substantive difference?
 
The odds of winning definitely did not change as a result of the glitched picker.

However, the expected winnings for a person using the glitched picker were reduced slightly. This has a net financial benefit to the owners of the lottery, so I think they should have to payout some sort of penalty or refund.

The key here is the shared pot. If the winners have to split a fixed pot evenly, it benefits the lottery owners to have a skewed distribution of selected numbers.
 
And I would think (but haven't done any calculations) that it would barely effect the actual winnings, either - at least of the bigger prices. The difference would be much more drastic for small prices (percentage wise).

If you clump winners together I would not be supprised if there is little effect assuming that the pot grows if there is no winner, and there are no winners frequently. It could result in a larger pot being split more ways being a more common result.
 
The odds of winning definitely did not change as a result of the glitched picker.

However, the expected winnings for a person using the glitched picker were reduced slightly. This has a net financial benefit to the owners of the lottery, so I think they should have to payout some sort of penalty or refund.

The key here is the shared pot. If the winners have to split a fixed pot evenly, it benefits the lottery owners to have a skewed distribution of selected numbers.

Maybe maybe not. If a set amount from the total take goes into the pot, and say there are 5 tickets with a single random number on it for every random number set selected. You will share the pot with 5 times as many people but someone will win 1/5 the time, so it would seem to be a wash.

So it might not effect the odds of winning or the likely size of your pot. I am sure it does not effect the first, I am uncertain in part because of uncertain about how it operates, about the second.
 
However, the expected winnings for a person using the glitched picker were reduced slightly. This has a net financial benefit to the owners of the lottery, so I think they should have to payout some sort of penalty or refund.

The key here is the shared pot. If the winners have to split a fixed pot evenly, it benefits the lottery owners to have a skewed distribution of selected numbers.
This is false. If in every lottery the owners have to pay out X dollars, they don't care who gets the money. Split it, burn it, convert it to piles of Batman figures, whatever.

In fact in reality they probably like it, since presumably they make more money on an unwon auction (prize gets larger next time but not enough?) than a won auction, and this will result in more unwon auctions.
 
The odds of winning definitely did not change as a result of the glitched picker.

However, the expected winnings for a person using the glitched picker were reduced slightly. This has a net financial benefit to the owners of the lottery, so I think they should have to payout some sort of penalty or refund.
No. Lotterys have fixed prizes at lower levels. The jackpot for all numbers correct is calculated by subtracting the fixed prizes from the total prize pool. The number of people the jackpot is shared between does not affect the jackpot's total value. Which is what GA said while I was typing.
 
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This is false. If in every lottery the owners have to pay out X dollars, they don't care who gets the money. Split it, burn it, convert it to piles of Batman figures, whatever.

In fact in reality they probably like it, since presumably they make more money on an unwon auction (prize gets larger next time but not enough?) than a won auction, and this will result in more unwon auctions.


I guess I was assuming that if the winning numbers were not picked by anybody, the lottery owners would pocket the jackpot. It looks like that is not the case.

Lottery owners aside, the expected value of a ticket bought with the glitched machine is still lower (assuming multiple people used the machine). The difference is slight, but it's still a difference. As an extreme example, what if everybody used that machine and the glitch generated the numbers 1-2-3-4-5-6-7 every time?
 
Yes. You're almost certainly not understanding it. The "specific case" you present is too specific to be useful in an analytic context; it's got too much information, from too many unfounded assumptions.

Awhaaa?

The case is too specific, with too much information?

That's a first, I have to admit that.

They say the glitch may affect the number of people that have to share the price. It doesn't affect the chances of winning.

Quite important, though.

Continuing with my simple example from before. If the RNG selected always the same sequence your chances of winning would be the same, but if you won you would have to share the price with everyone that used it. This RNG would be very bad, because you would never be able to win a big amount of money by using it.

We don't know how bad it was.

Is that fair?

Yes it is fair. What you lose in heads, you make up for in tails. As the outcome of the coin toss wasn't decided before you bought your ticket, then the advantage you'd have IF it came up tails balances out the disadvantage if it came up heads

It may be "fair" if we look at the single gambler in the very long run, but it isn't "fair" to the group of people who got "heads" selected for them.

No. You're misinterpreting the numbers.

Out of 1000 trials, the difference between the highest win percentage (always-picks-1) and the lowest win percentage (semi-biased) is 0.034 or 3.4%

Out of 1000000 trials, the difference between the highest win percentage (always-picks-1) and the lowest win percentage (semi-biased) is 0.001 or 0.1%

Out of 100000000 trials, the difference between the highest win percentage (fair picker) and the lowest win percentage (2-6 picker) is 0.000077 or 0.0077%

If ben m had the time/processing power, he could have continued with ever-increasing numbers of trials, and the difference would get closer and closer to zero.

There's a problem with that: In a lottery like this, you don't get to play an infinite amount of times. You can only have so many drawings, realistically. E.g., in this particular Lotto game, we have 52 drawings a year, and it's been going on since 1989, 18 years ago.

The error dates back to December 11, 2002 and was fixed December 21, 2006, which gives approx. 208 drawings. Run that many trials and see that the difference is quite noticeable.

The rules probably already limit damages to the price of the ticket so I did address the issue by saying they should get their money back and void the ticket.

Not to my knowledge. If it did, the organization would be compelled to give the money back. They aren't.

Have you got any links to what the actual problem was? I'm having a hard time conceiving how the Lucky Pick machine could have accidently skewed the probabilities for just 1-9 lower than the other numbers. And how much of difference are we talking about? Are there statistics available for how often each number is picked by Lucky Pick and for regular players?

The links I have seen are all in Danish. We don't know the exact difference, but you can see statistics here:

danskespil.dk

Click on "Spil". Next level, click on "LOTTO". Next level, click on "LOTTO". Sidebar, click "Statistik".

I specifically ran the increasing-numbers simulations to forstall you from saying that. No, the biased picker does not have a lower chance of winning; all of the "win percentage" quantities are asymptotically approaching 1/6, and scattering around it with a Gaussian error of 1/sqrt(n).

Hang on a minute, I'll post a few more decades of the sim when they're finished running.

You don't need to. Just run 208 times, and see what the difference is. That's the real-world number we have to deal with.

Yes yes, I completely concur with the fact that their chances of winning were not affected. The only thing that affects that is the ball picker.

What I am talking about is what people think they are buying. And what they think they are buying (a totally random selection) is not what they bought (a slightly biased selection). Given that lottery marketing sets out to exploit superstition and poor understanding of probability, I think it's perfectly reasonable for people who bought their tickets that way to feel disgruntled.

Lotteries are all about emotions, feelings, irrationality. I would be willing to bet that many lottery players don't understand that sequential numbers have the same chance of winning as any other set, for example. And lotteries pander to and exploit these sorts of irrationalities. For example, the UK lottery slogan 'it could be you' is almost a lie. It almost certainly will not be you. It could be, but I'd be willing to bet £500 it won't be. It will probably be someone. But not you.

It's almost true that lotteries are all about emotions, feelings, irrationality. The one thing that is not, is how the numbers fall. If people expect that their coupon is filled with random numbers, they have a right to complain when it turns out it isn't the case.

And what you are missing is that it does not matter. The only effect is that there might have been more or less people winning particular pots.

I'd say that's pretty darn important.
 
Well, that took longer than I expected. Here ya go. I can't vouch that the last set of numbers isn't running into floating-point noise, but I'm pretty sure that the integers are all OK.

out of 10000 trials
fair picker wins 1656 or 0.1656
2-6 picker wins 1747 or 0.1747
semi-biased picker wins 1674 or 0.1674
always-pick-1 wins 1699 or 0.1699

out of 100000 trials
fair picker wins 16689 or 0.16689
2-6 picker wins 16614 or 0.16614
semi-biased picker wins 16403 or 0.16403
always-pick-1 wins 16956 or 0.16956

out of 1000000 trials
fair picker wins 166236 or 0.166236
2-6 picker wins 166776 or 0.166776
semi-biased picker wins 166148 or 0.166148
always-pick-1 wins 166588 or 0.166588

out of 10000000 trials
fair picker wins 1666822 or 0.166682
2-6 picker wins 1666378 or 0.166638
semi-biased picker wins 1666800 or 0.16668
always-pick-1 wins 1666327 or 0.166633

out of 100000000 trials
fair picker wins 16673171 or 0.166732
2-6 picker wins 16666089 or 0.166661
semi-biased picker wins 16667073 or 0.166671
always-pick-1 wins 16669408 or 0.166694

out of 1000000000 trials
fair picker wins 166651800 or 0.166652
2-6 picker wins 166647758 or 0.166648
semi-biased picker wins 166670941 or 0.166671
always-pick-1 wins 166681496 or 0.166681

out of 10000000000 trials
fair picker wins 1666706825 or 0.166671
2-6 picker wins 1666708965 or 0.166671
semi-biased picker wins 1666663693 or 0.166666
always-pick-1 wins 1666664380 or 0.166666
 
As an extreme example, what if everybody used that machine and the glitch generated the numbers 1-2-3-4-5-6-7 every time?
If the numbers drawn meant the ticket 1-2-3-4-5-6-7 was not a winner the prize fund would roll over.

If the ticket was a jackpot then the winners would share the jackpot. Given the jackpot = stake less fixed prizes less charitable contribution (or profit) less admin fees. They would on average get back less than the stake (subject to roll over).

If the ticket won a fixed prize (for more than the stakes and roll over income) it would get interesting as the prizes would exceed the funds available for that draw.
 
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There's a problem with that: In a lottery like this, you don't get to play an infinite amount of times. You can only have so many drawings, realistically. E.g., in this particular Lotto game, we have 52 drawings a year, and it's been going on since 1989, 18 years ago.

No no no no no. We're talking about statistics here, not law. If you want to examine a particular case, and argue that you were defrauded of some money that you deserved, then statistics aren't really going to help you.

Ben m can run the case for 208 drawings, and he'll get one result. Then, he can run it again for another 208 drawings, and he'll get a completely different result, but with similar characteristics to the first one - that's the definition of a random draw. We could produce results that showed that a biased draw gives a higher probability of winning with ben m's approach, which is one of the limits of Monte Carlo simulations.

Edited to add: Ben m beat me to the punch. His re-run with 1000 cases shows that a biased draw produced more winners than a standard draw.
 
Well, that took longer than I expected. Here ya go. I can't vouch that the last set of numbers isn't running into floating-point noise, but I'm pretty sure that the integers are all OK.

out of 10000 trials
fair picker wins 1656 or 0.1656
2-6 picker wins 1747 or 0.1747
semi-biased picker wins 1674 or 0.1674
always-pick-1 wins 1699 or 0.1699

out of 100000 trials
fair picker wins 16689 or 0.16689
2-6 picker wins 16614 or 0.16614
semi-biased picker wins 16403 or 0.16403
always-pick-1 wins 16956 or 0.16956

out of 1000000 trials
fair picker wins 166236 or 0.166236
2-6 picker wins 166776 or 0.166776
semi-biased picker wins 166148 or 0.166148
always-pick-1 wins 166588 or 0.166588

out of 10000000 trials
fair picker wins 1666822 or 0.166682
2-6 picker wins 1666378 or 0.166638
semi-biased picker wins 1666800 or 0.16668
always-pick-1 wins 1666327 or 0.166633

out of 100000000 trials
fair picker wins 16673171 or 0.166732
2-6 picker wins 16666089 or 0.166661
semi-biased picker wins 16667073 or 0.166671
always-pick-1 wins 16669408 or 0.166694

out of 1000000000 trials
fair picker wins 166651800 or 0.166652
2-6 picker wins 166647758 or 0.166648
semi-biased picker wins 166670941 or 0.166671
always-pick-1 wins 166681496 or 0.166681

out of 10000000000 trials
fair picker wins 1666706825 or 0.166671
2-6 picker wins 1666708965 or 0.166671
semi-biased picker wins 1666663693 or 0.166666
always-pick-1 wins 1666664380 or 0.166666

And if you run 208 trials?
 
Why? IF your odds of winning and expected pay out on a win are the same what does it matter if you are more or less likely to be sharing a pot?

According to the article, the expected pay out is not the same for the group.

Not the person. The group.

No no no no no. We're talking about statistics here, not law. If you want to examine a particular case, and argue that you were defrauded of some money that you deserved, then statistics aren't really going to help you.

Ben m can run the case for 208 drawings, and he'll get one result. Then, he can run it again for another 208 drawings, and he'll get a completely different result, but with similar characteristics to the first one - that's the definition of a random draw. We could produce results that showed that a biased draw gives a higher probability of winning with ben m's approach, which is one of the limits of Monte Carlo simulations.

Edited to add: Ben m beat me to the punch. His re-run with 1000 cases shows that a biased draw produced more winners than a standard draw.

Then, run a series of 208 trials and see what you'll get on average.

What you will get is a lower probability of win - right?
 

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