The retailing manager of a food chain wishes to determine whether product location will have any effect on the sale of pet toys. Two factors are to be studied: (1) height of shelf: top, middle, bottom; and (2) location in aisle:front, middle, rear. A random sample of 18 stores was selected, and 2 stores were randomly assigned to each combination of shelf height and aisle location. The size of the display area was constant for all 18 stores. At the end of a one-week trial period, the sales of the product in each store were as follows: