Why lottery players don't really pick at random

Five million Dutch lottery tickets under the microscope: they reveal our birthdays, our age … and even our postcode.

A study of 5 million tickets

Four Dutch researchers analysed 5,108,343 combinations played online in the Dutch Lotto (6 from 45) between 2010 and 2012. They also studied a promotional game by Holland Casino, where players had to predict four roulette spins. Their question: which numbers do people choose when they are free to choose?

The 11 versus 7 showdown

At random, each number would appear on about 13.3% of tickets. In reality, 11 is picked on 16.5% of tickets, with 7 right behind on 16.3%. The least loved? 38 (10.5%) and 37 (10.3%). At the casino, 7 wins (4.19%), ahead of 8.

"My" numbers

The researchers knew the online players' date of birth and postcode. Result: people pick their day of birth on 21% of tickets, well above the 13.3% expected by chance. Next come the year, the month, their age, and then the postcode. At the casino, the day of birth is picked about three times more often than expected.

Tickets that want to "look" random

Among even numbers, round tens are picked slightly less: 12.7% versus 13.2% in the Lotto. The authors see this as a wish for tickets that "look random". Players also prefer numbers in the middle of the play slip and avoid the edges. The most played ticket, 1 11 21 31 33 41, was picked 1,213 times: it's a pattern on the slip. Lines and diagonals make up 0.9% of tickets, against 0.009% at random.

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