The planned opening of a full-service supermarket in the Hill District presents a rare opportunity to learn why people purchase the foods they do and, by extension, what influences them to make healthy choices.

It has been suggested that people who have easy access to a variety of affordable foods will make better nutritional choices and live healthier lives. To that end, the Obama administration has committed $400 million to bringing healthy food retailers to underserved urban and rural communities.

But there are few studies that have taken a detailed before-and-after look at how a former "food desert" can be changed by adding a new market to the neighborhood. That's what researchers from the respected Rand Corp. -- supported by a $2.7 million grant from the National Institutes of Health and help from the University of Pittsburgh Center for Social and Urban Research and the Hill House Association -- hope to accomplish with a five-year study centered around the Shop 'n Save market that is to open in late 2011.

This unique collaboration is made possible because of Rand's significant presence with an office in Pittsburgh. The study is important because a greater understanding of the impact of a local grocer could strengthen public policies designed to improve the health of Americans.

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