With your major in food science, you were delighted to find work with Sheffield Farms, a medium-sized supermarket chain in the Middle West. Your first assignment was to a small group that studies consumer food preferences and habits. The group leader is Shirley Gomez. One of your tasks was to research the readability of the new food labels required by the Food and Drug Administration.

You had sought volunteers among people shopping in Sheffield Farm stores. You had provided them labels to read and then questioned them on their understanding of the information on the label. To a high degree they understood the information provided about fat, cholesterol, fiber, protein, and so forth. But as you were conducting your research, you wondered how many Sheffield Farms customers actually made decisions based on the labels.

You brought the idea up to Shirley. "Good thought," she said. "How would you go about it?"

"I can think of three ways," you said. "Observation for one. Simply watch to see how many people read a food label when they take food off a shelf. Another would be to ask people at checkout how often they read food labels. Third, we could take some common purchase like cereal out of customers' baskets, and without showing them the food label, try to find out how much of the information on the label they're actually aware of."

"Has anyone done this?" Shirley asked.

"My preliminary search in the journals and on the Web hasn't turned...