16.10 Wheat prices.
Example 7.13 (pages 385-386) reports the results of a small survey that asked separate samples of 5 wheat producers in each of January and July what price they received for wheat sold that month. Here are the data:
wheat
Month | Price of wheat ($/bushel) | ||||
January | $6.6125 | $6.4775 | $6.3500 | $6.7525 | $6.7625 |
July | $6.7350 | $6.9000 | $6.6475 | $7.2025 | $7.0550 |
The stemplot on page 386 shows a large difference between months. We cannot assess Normality from such small samples. Carry out by hand the steps in the Wilcoxon rank sum test for comparing prices in January and July.