In December 2009, Domino’s Pizza, Inc. released untraditional ads citing that its old recipe for pizza produced crust that tasted like cardboard and sauce that tasted like ketchup. Domino’s Pizza claims that its reformulated pizza is a vast improvement over the old recipe; for instance, garlic and parsley are now baked into the crust and a new sweeter, bolder tomato sauce is used. Suppose 20 customers are asked to sample the old recipe and then sample the new recipe. Each person is asked to rate the pizzas on a 5-point scale, where 1 = inedible and 5 = very tasty.

The ratings are shown in Table 20.19; the data labeled D om ino’s Pizza can also be found on the text website. Do these data provide sufficient evidence to allow us to conclude that the new recipe is preferred to the old recipe? Use α = 0.05.