Scanners themselves tend to be very accurate. A lot of the errors are due to mispriced tags on items and incorrectly entered prices in the computer that interacts with the scanner, rather than the scanner itself. The errors tend to come outside of the equipment. Errors also are made when a supermarket chain downloads the current prices for items from a computer at the chain's regional office. They even can come from shoppers removing or switching price tags in the aisles.
Hyman tells shoppers to expect an occasional error.
The average supermarket's prices are more than 95 percent accurate, and SCP participants average more than 98 percent accuracy. But with most supermarkets stocking between 30,000 and 40,000 items, and bigger facilities exceeding 75,000, mistakes are inevitable. So pay attention at the check-out counter. The Scanning Certification Program is an independent quality-control system founded in 1991 by a coalition of Pennsylvania food merchants, concerned consumers, labor union representatives, and state regulators. In addition to the independent certification process, it provides an educational program for employees and clear strategies for managers to improve the store's accuracy rating.