Frequently Asked Questions
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What's this site doing exactly?
The winners of a scratch off lottery ticket are determined at printing and randomly distributed throughout the tickets sold in stores. As tickets get sold, for some games, the winning tickets sell faster or slower than others. For example, imagine a jar was filled with 100 jelly beans and 2 were red, and the rest were green. If you took out 20 jelly beans and they were all green, the next person would have a better chance of getting the red bean.
For every state scratch off game, the Virginia Lottery lists on their web site how many winning tickets are unclaimed for each prize. That information can be used to figure out which games have better or worse odds than their initial odds at printing.
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How does it work exactly?
I estimate for each game how many tickets remain unsold. For each prize, I compare how many winning tickets are left and compare to the number of tickets left. Some prizes will have their overall odds improve, if tickets are being bougth at a faster rate than prizes are being claimed. For example if 20% of tickets have been sold but all four top prizes are still unclaimed, than the odds have improved from what's printed on the tickets.
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Ah, so I should definitely play the games you recommend?
Um, maybe? A lot of assumptions have to be made about the calculations. For example, we don't actually know how many tickets have been sold - the Virigina Lottery may not even know that per game, they don't share that information. I have to use the claim rate of the common small-prize tickets to approximate how many tickets are left unsold. That's just one assumption that is required.
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Wait, what else are you assuming? And what's wrong with these assumptions?
Well, for example the most common prize can be just winning back your original $1 wager. Not everyone bothers to claim a $1 "winning" ticket. The Virginia Lottery has said that 1.5% of total prize values goes unclaimed. Presumably most of that is the smallest prizes.
In any event, using the $1 prize claim rate to estimate how many tickets are left seems wrong: when I do that it shows that every game is getting worse odds which doesn't make sense. I think using the second lowest prize is better, so that's what I do, but it's stil as assumption.
Another, bigger, problem in that people who win $1 or $5 can claim it easily at a retailer. So, those prize claims will fill in over a weekend. But if you win $5000 you will have to go a lottery office, so those will never be claimed on a weekend.
For a big prize, like $500,000, those have taken ~2 weeks to claim after purchase. So, a game may look like it has improved odds, but in reality a winnig ticket could have been sold yesterday
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So, it doesn't matter what ticket I buy?
Well, it is probably a bad idea to buy tickets where we know the top prizes are all gone or have been claimed at a higher rate than sales. The game recommendations here should be better than buying an actively bad game or picking one randomly.
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What is expectation value? And why do they all seem pretty bad, especially the cheap games?
Expectation value is the statistical value of $1 played on that particular ticket. Imagine there were 100 $1 tickets and half paid out $2, half nothing. The expectation value would be $1 because if you played forever (or if you bought every ticket), you'd break even (Spend $100 on tickets, win $100 back on the 50 winners). Expectation value depends on the odds, but also the payout and the ticket price. Most games have a house edge so that the prizes are less than the total revenue for selling the tickets.
The Virginia lottery states that 60% of revenue goes to prizes, but that is not a constant by game. Some games have an expectation value starting around 60 cents per dollar spent, others start closer to 80 cents. That means that if you sort of played infinitely, you'd recover that much of your wagers.
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So if the expectation value gets over $1, I should definitely play?
Sort of? It depends on the cost of the ticket, and your tolerance for risk/loss. If the expectation value is like $1.01, would you spend $1000 for the statistical edge of winning maybe (probably) $10?
Also, the highest expectation values tend to be the highest cost tickets, so those are all games one can't play for very long before hitting one's spending limit. And then there is the ever-present risk that the expectation value is being driven by an assumption about a top prize remaining unsold when it is just unclaimed and the winner is waiting a a week or more to claim it.