The manufacturer of felt-tip markers investigated whether a proposed new display, featuring a picture of a physician, is more effective in drugstores than the present display, featuring an athlete and located in the stationary area. Twenty-four drugstores of similar characteristics were conveniently chosen for the experiment. They were assigned, at random in equal numbers, to one of the following three treatments: Show all work.

(1) Use the existing display (with an athlete) in the stationary area (2) Use the new display (with a physician) in the stationary area (3) Use the new display (with a physician) in the checkout area.

Sales with the present display (featuring an athlete, displayed in the stationary area) were recorded for a three-week period (i.e. "previous sales"). Then the new display was set up in the 16 stores receiving it, and the sales for the next three weeks were recorded in all 24 stores (i.e. "new sales"). The response variable is the change in sales ("new sales" minus "previous sales").

The selected output is below:

Source DE SS MS F P Factor 2538.2 Error 273.8 Total Individual 954 CIs For Mean Based on Pooled StDev Level N Mean StDev B -1. 500 2. 619 WNP 8 15. 625 6.886 8 29.125 12.933 12 24 36