From Exercise 8.5, test to see if the underlying variances for the four plot yields are the same. Use a test level of cu = 0.05. Some varieties of nematodes (roundworms that live in the soil and are...

From Exercise 8.5, test to see if the underlying variances for the four plot yields are the same. Use a test level of cu = 0.05.

Some varieties of nematodes (roundworms that live in the soil and are frequently so small they are invisible to the naked eye) feed on the roots of lawn grasses and crops such as strawberries and tomatoes. This pest; which is particularly troublesome in warm climates, can be treated by the application of nematicides. However, because of size of the worms, it is difficult to measure the effectiveness of these pesticides directly. To compare four nematicides, the yields of equal-size plots of one variety of tomatoes were collected. The data (yields in pounds per plot) are shown in the table. Use a nonparametric test to find out which nematicides are different.