Question

a market research firm is studying the effects of price and type of packaging on sales of a particular product. twenty - seven stores with shoppers of similar characteristics will be used in the study. the nine combinations of three price levels and three packaging types are the treatments of interest. total sales of the product over a seven - week period will be recorded. which of the following describes the best design to use for the study?
a a completely randomized design. randomly assign the nine combinations of price level and packaging type so that three stores use each combination.
b a completely randomized design. randomly assign the three price levels so that nine stores use each price level.
c a completely randomized design. randomly assign the three packaging types so that nine stores use each type of packaging.
d a randomized block design. use packaging as a block. randomly assign the nine combinations of three price levels and three packaging types so that three stores use each combination.
e a randomized block design. use packaging as a block. randomly assign nine stores to each packaging type, then randomly assign price level to three stores within each block.

Explanation:

• A completely randomized design is appropriate here as there is no need to block based on any prior - known factors (since stores have similar shopper characteristics).
• We have 9 treatment combinations (3 price levels × 3 packaging types). With 27 stores, we need to assign 3 stores per treatment combination.

Answer:

A. A completely randomized design. Randomly assign the nine combinations of price level and packaging type so that three stores use each combination.