A new bias? The "lucky store effect"

The Monkey Cage cites a paper by Jonathan Guryan of the Graduate School of Business, University of Chicago, and Melissa Kearney of the University of Maryland that tries to explain the following phenomenon:

In the week after a large-prize winning ticket has been purchased at a given store, that store experiences a 12 to 28% relative sales increase in lottery ticket sales. This increase fades over time, but the store’s lottery ticket sales remain elevated for up to 40 weeks. This effect increases with the size of the jackpot and with the economically disadvantaged proportion of the population.

What’s interesting about this finding is that previous research has shown that people decrease the amount of money bet on certain lottery numbers after those numbers come up winners. So they go to the store that sold the last lottery ticket, but don’t pick any of the numbers from the last jackpot? How can these apparently contradictory findings be resolved? Guryan and Kearney come up with an idea they call the “lucky store effect” in which “consumers erroneously increase their estimate of the probability a ticket bought from the winning store will itself be a winner.”

Continue reading the post here.

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