sold and their prices; and (2) household scanner panels, which are usually random samples of households in which household members are asked to scan in the UPC of the items they have purchased, using scanners provided to them (see Box 3-1 for a summary of the data content of household scanner panels).
ACNielsen (formerly, A.C. Nielsen Company) and Information Resources, Inc. (IRI), are the two major producers of these types of datasets. For point-of-sale data, ACNielsen and IRI purchase price and item data from the scanner systems of cooperating retail outlets (the ACNielsen data collection is called Scantrack Services; the IRI collection is called Custom Store Tracking). Supermarket scanner data do not include fruits and vegetables, some prepared foods, and other products that lack UPC codes. They also do not cover restaurants or other food outlets.
Household scanner panel data are generated by randomly selected households, in which a household member scans in the household’s food purchases from all types of stores over a week’s time. As currently designed, these data provide limited demographic characteristics. Information collected on products with a UPC includes price, quantity, and promotional information. For items that lack a UPC, such as meat and fresh produce, participants are asked to identify the type of item and its weight. Both ACNielsen and IRI conduct these types of panel surveys for nationally representative samples of more than 61,500 and 50,000 households, respectively (the ACNielsen data collection is called the HOMESCAN Consumer Panel; the IRI collection is called the Combined Outlet Consumer Panel).1
Researchers inside or outside the government must purchase scanner data, although the cost need not be high, depending on the amount of data required. A study by the Food and Nutrition Service estimated the cost of 2 months of scanner data collection for a supermarket chain to be $35,000. To consider this figure in context, the study indicated that the National Survey of Food Stamp Program Participants in 1996 cost $1.7 million. Purchase of the necessary scanner data for applications that required many months or years of observations for many outlets could, of course, entail substantial costs.