Question: Suppose you wish to determine whether there are differences in the average price among three major supermarkets in a given city. Your randomly select eight regularly bought brand items, each distinct item of the same brand, and observe their unit prices (in dollars) at each supermarket. The following sample data were obtained:

Supermarket

Item A B C

1 2.84 2.90 2.82

2. 0.51 0.56 0.51

3. 1.08 1.10 1.08

4. 3.75 3.80 3.70

5. 0.77 0.75 0.77

6. 1.59 1.54 1.63

7. 0.82 0.77 0.77

8. 0.65 0.68 0.59

a. Why there is a need to block the items?

b. What other aspects should be considered in this situation as the prices are being recorded

c. Graph the sample data. Are any differences in the average price for the three supermarkets apparent to you. Explain?

d. Use the analysis of variance procedure to test the null hypothesis of no treatment effect.