People respond to e-mail randomly, cycles

CHICAGO, Nov. 24 (UPI) -- A study over a 3-month period at a European university found that people e-mail randomly, but in cycles, U.S. researchers said.

Luis Amaral of Northwestern University in Chicago and colleagues studied e-mails sent to and received from more than 3,000 e-mail accounts at a European university. The researchers created a mathematical model that showed people send e-mail randomly -- a finding that challenges a recent paper that people respond to e-mails in the most efficient way, dubbed the "rational model."

"I was not convinced, since I don't do it in a rational way," Amaral said in a statement.

However, if a random model was correct, there would be a typical interval between e-mails -- which Amaral did not find.

The study, published online by the Proceedings of the National Academy of Sciences, found e-mail was sent randomly but there were non-random intervals during which people didn't send e-mail -- when they were sleeping.

"During the day, you send e-mails, but then you go home, or go away for the weekend and you don't send e-mails," he said. "These data were from a few years ago, and in Europe, this was especially the case, since many people didn't have the Internet at home."

The model explains the data that show people have cycles in which they use certain services, the researchers said.