A farmer is concerned that a change in fertilizer to an organic variant m ight change his crop yield. He subdivides 6 lots and uses the old fertilizer on one half of each lot and the new fertilizer on the other half. The following table shows the results.

Lot Crop Yield Using Old Fertilizer Crop Yield Using New Fertilizer 1 10 12 2 11 10 3 10 13 4 12 9 5 12 11 6 11 12

a. Specify the com peting hypotheses to determ ine w hether the m edian difference between the crop yields differs from zero.

b. Calculate the value o f the W ilcoxon signed-rank test statistic T. Do not assume that the sampling distribution of T is norm ally distributed.

c. At the 5% significance level, w hat is the decision rule?

d. Is there sufficient evidence to conclude that the median difference between the crop yields differs from zero?

Should the farmer be concerned? Explain.