A department store shifted its main entrance closer to the street, and the number of people walking into the store each day rose by half. Over the same weeks, however, the store's total sales fell slightly. Which of the following, if true, best explains this apparently contradictory result?

The count at the door rose, but the people it counted were passing through rather than buying, so the extra footfall added nothing to sales; meanwhile the crowding cost the store some of the customers who did buy. That accounts for both halves of the result at once. Unchanged staffing, unchanged advertising and the presence of rival shops were all true before the entrance moved as well, so none of them explains a change.