CHAMPAIGN, Ill. -- Supermarkets can significantly boost their Center Store sales by using signage on displays that limit quantities or suggest that consumers purchase a specified number of items, a study conducted by the University of Illinois here has revealed.
The study was conducted by Brian Wansink, associate professor of marketing, who has been dubbed "The Professor of Packaged Goods" by ABC News, and associates Robert Kent and Stephen Hoch. It was published earlier this year in the Journal of Marketing Research.
Displays of 21 products in 89 grocery stores in Chicago, Philadelphia and Iowa were tracked for the study.
"Shoppers buy more if they see a numerical display; that is, a display that mentions a specific purchase quantity number," the report states.
"When a display suggests a specific number, it can upwardly bias how much a person buys," Wansink said.
As an example, he cited a Sioux City, Iowa, supermarket that had a sign stating canned soups were "79 cents each -- no limit." Shoppers typically bought three or four cans. But when the sign was changed to read "79 cents -- limit 12 per person," they typically purchased seven cans each.
The study found evidence that suggestions of "promotional stockpiling" can accelerate consumption.
"Such effects, however, appear to be highly category-specific," the report stated. "Consumer stockpiling has been shown to generate temporary consumption increases for cookies and fruit juice, but significant increases have not been found for detergent or ketchup."
Mark Polsky, senior vice president, at Magruder, Rockville, Md., said he has found that numerical displays do help to build sales.
"There are a lot of things we can do to increase awareness," he said. "You put limits in the ad and say 'supply is limited -- no rainchecks.' "
Magruder's also uses "multiple" pricing to stimulate sales.
"If an item normally sells for $1.99, and we offer it at 2 for $4, we increase our volume. Don't ask me why," Polksy said.
However, Polsky said he has not had as much success with "buy-one-get-one-free" offers, or BOGOs.
"We tried a couple of programs and it has just not been successful. People might have the perception that we raise the prices when we run BOGO events," he said.
Other retailers, like Big Y Foods and ShopRite, limit the number of items that can be purchased because of their electronic frequent shopper programs.
"Because we have been into electronic couponing with our frequent shopper card, as a matter of practice we have limited many of the items that we put through that program to five items or deals, depending on the offer," Donald D'Amour, chairman of Springfield, Mass.-based Big Y Foods, told SN.
"We didn't do this for purposes of increasing sales," he said.
"If you put a limit you are saying that it is a value, but if it isn't a value you are not going to fool too many people," D'Amour said.
Wakefern Food Corp., the Elizabeth, N.J.-based cooperative wholesaler that services ShopRite Supermarkets, also regularly limits the number of items that can be purchased with its Price Plus frequent shopper card.
For example, in its July 5 weekly circular, ShopRite featured a three-slice box of Ellio's frozen pizza for 49 cents, limit four boxes.
The same week two-liter bottles of Pepsi products were featured at 79 cents each. The offer included Pepsi, Pepsi Caffeine Free, Diet Pepsi, Diet Caffeine-Free Pepsi, Lipton iced tea, Schweppes ginger ale, Mountain Dew, Wild Cherry, Hawaiian Punch, Mug root beer and Slice, and shoppers were allowed to take up to four discounts of each variety, for a total of 44 bottles.
Officials at Wakefern could not be reached for comment.
Peter Jost, head buyer, grocery, Harps Food Stores, Springdale, Ark., said his chain usually does not suggest quantities to shoppers.
"We generally restrict our limits to loss leaders to avoid out-of-stocks. We find that works well," he said.