Toronto, Sep 30 : An empty store shelf tempts shoppers to buy the next best thing, says a new study.

"Sold-out products create a sense of immediacy for customers; they feel that if one product is gone, the next item could also sell out," said Paul Messinger, professor at the University of Alberta (U-A) in Canada, who conducted the study.

"Our research shows there's also an information cascade, where people infer that if a product is sold out, it must have been good and therefore a similar available product will also be desirable," he said.

The study found 61 percent shoppers would buy a particular five-hour ski pass for $20, but that figure rose to 91 percent when they thought a 10-hour ski pass for the same mountain slope for $40 had sold out.

A similar study of Merlot wines found 49 percent of consumers would buy a bottle if they had one choice, but when they thought a similar wine had sold out next to it on the shelf, nearly twice the number of shoppers would take home the available bottle.

"The use of sold-out signs creates a sense of urgency," said Messinger. The annual phenomenon of a hot toy selling out at Christmas can also be attributed to the information cascade theory, he said.

"You're dealing with toys that parents don't know if their children will like, but millions of consumers are buying it, so they infer that because the item is being purchased, it must be good."

These findings were published in the Journal of Retailing. (ians)