New production methods stressing teamwork have recently been instituted at car manufacturing plants in Detroit. Three teamwork production methods are to be compared to see if they are equally effective. Since large deviations often occur in the numbers produced daily, it is desired to test for equality of medians (rather than means).

Samples of daily production volume for the three methods are as follows. Assume that these are random samples from the populations of daily production volume. Use the median test to help determine whether the three methods are equally effective.

Method A: 5, 7, 19, 8, 10, 16, 14, 9, 22, 4, 7, 8, 15, 18, 7

Method B: 8, 12, 15, 28, 5, 14, 19, 16, 23, 19, 25, 17, 20

Method C: 14, 28, 13, 10, 8, 29, 30, 26, 17, 13, 10, 31, 27, 20