Method
- Given data, that is, a matrix with rows (the blocks), columns (the treatments) and a single observation at the intersection of each block and treatment, calculate the ranks within each block. If there are tied values, assign to each tied value the average of the ranks that would have been assigned without ties. Replace the data with a new matrix where the entry is the rank of within block .
- Find the values:
- ,
- The test statistic is given by . Note that the value of Q as computed above does not need to be adjusted for tied values in the data.
- Finally, when n or k is large (i.e. n > 15 or k > 4), the probability distribution of Q can be approximated by that of a chi-square distribution. In this case the p-value is given by . If n or k is small, the approximation to chi-square becomes poor and the p-value should be obtained from tables of Q specially prepared for the Friedman test. If the p-value is significant, appropriate post-hoc multiple comparisons tests would be performed.
Read more about this topic: Friedman Test
Famous quotes containing the word method:
“I have a new method of poetry. All you got to do is look over your notebooks ... or lay down on a couch, and think of anything that comes into your head, especially the miseries.... Then arrange in lines of two, three or four words each, don’t bother about sentences, in sections of two, three or four lines each.”
—Allen Ginsberg (b. 1926)
“Women are denied masturbation even more severely than men and that’s another method of control—they’re not taught to please themselves.... Most women—it takes them a while to warm up to the “situation” but once they get into it, I’m sure they’re going to get just as hooked as—well, everyone I know is!”
—Lydia Lunch (b. 1959)
“Frankly, I adore your catchy slogan, “Adoption, not Abortion,” although no one has been able to figure out, even with expert counseling, how to use adoption as a method of birth control, or at what time of the month it is most effective.”
—Barbara Ehrenreich (b. 1941)