Shelf Level
Shelf Height May Affect the Volume of Sales

Shelf Level
Shelf height may affect the volume of sales for a product.In order to determine whether or not there is any effect on average sales due to product shelf height,a marketing consultant chooses four typical outlets,a supermarket,a drug store,a discount store,and a variety store,and for one week places the product chosen at one eye level.A resting week follows and the product is moved to another height and so on for three different heights.The number of units sold per week at each location and height are: $$\begin{array}{l}\text { Shelf Level }\\\begin{array} { | l | c c c | } \hline \text { Store } & \text { Above } & \text { Even } & \text { Below } \\\hline \text { Discount } & 54 & 55 & 49 \\\text { Supermarket } & 63 & 60 & 56 \\\text { Drug Store } & 52 & 52 & 47 \\\text { Variety } & 44 & 48 & 41 \\\hline\end{array}\end{array}$$
-Compute the total sum of squares (SST).