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Comment by bryanlarsen | Hacker News Reader

According to [1] the expected average return on a $2 ticket is $1.34. That's accounting for the almost certain chance you'll have to share the prize, the lump sum payout and taxes.

1: http://fivethirtyeight.com/features/billion-dollar-powerball...

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> the almost certain chance you'll have to share the prize

What are you basing that on? I don't know what you mean by "almost certain", but to me that phrase means at least 90%, and the chance of two people hitting the powerball jackpot are substantially less.

During the last drawing they estimate that 75% of all possible numbers were chosen. This time there will be even more tickets sold and the possibility of doubling up is probably going to be higher than ever.

Currently, they're projecting 85% of all combinations will have been purchased for this upcoming drawing.

Wow, that drops it more than I would have thought.

There's an estimated 97% chance of a shared prize.

You're misreading. 538 says 97% chance of at least one prize. The EV calculation comes from the Federalist, which doesn't give an exact probability for a shared prize, but reduces the payout by 37% to account for it. This is based on another source, which also doesn't give a probability that I can see. (That probability might not be super helpful - you want the probabilities of one winner, two winners, three winners, etc. At some point it becomes rounding error, but I wouldn't be surprised if you want to go at least to three.)

But 538 guesses twice as many tickets sold as the Federalist does.

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