Speedy Spillovers

When a speedy cashier steps up to a register in a row of supermarket checkout stations staffed by ­slower-­moving clerks, a surprising “spill­over effect” occurs, write Alexandre Mas and Enrico Moretti, econo­mists at the University of California, Berke­ley. The other cashiers who can see the faster worker speed ­up.

Placing even a single superworker among slower ones will boost the speed of the entire group.

Mas and Moretti studied the productivity of 394 cashiers working for six stores in a nation­al supermarket chain. They found that the introduction of a single ­super­worker boosted the speed of the entire group by one percent. Such top achievers scanned and sometimes bagged 30 percent more items than their slowest counter­parts. The slower cashiers appar­ently felt “peer pressure” to pick up the pace in the presence of the faster scanner to avoid shame, or even informal or formal “sanc­tions” for ­free ­riding, the authors con­clude. And the closer a cashier was stationed to one of the speed demons, the more likely that cashier was to step it ­up. But the opposite did not happen. The faster workers seemed unaffected by the rate of their coworkers and didn’t flag. Once speedy, virtually always speedy, the authors found.

The sociology of the checkout world could save supermarket chains and other group production enterprises big money, Mas and Moretti write. Worker pro­duc­tivity is greater when ­high-­skilled and ­low-­skilled workers are scheduled on the same shift. For the firm they studied as a whole, achieving the opti­mum mix of workers could have saved 123,529 hours of labor an­nually. At current wages, this adds up to $2.5 million every ­year.

THE SOURCE: “Peers at Work” by Alexandre Mas and Enrico Moretti, in American Economic Review, March ­2009.

Photo courtesy of Flickr/Márcio Cabral de Moura