How can we find out why people buy at certain stores? Attitude surveys can be misleading, as this article shows, in that they may confuse attitudes which predispose patronage with those which result from patronage. A partial solution to this problem may be achieved by cross-tabulating customer rakings of competing stores with data on the relative size of their expenditures at each of these stores. The author is Associate Professor of Marketing at the Wharton School of Finance and Commerce, University of Pennsylvania.