Biostatistics

716 CHAPTER 13 NONPARAMETRIC AND DISTRIBUTION-FREE STATISTICS
Dialog box:
Session command:
Stat Nonparametrics Friedman MTB > FRIEDMAN C3 C1 C2
Type C3 in Response, C1 in Treatment and C2 in
Blocks. Click OK.
Output:
Friedman Test: C3 versus C1 blocked by C2
S 8.22 d.f. 2 p 0.017
Est. Sum of
C1 N Median RANKS
1 9 2.0000 15.0
2 9 2.6667 25.0
3 9 1.3333 14.0
Grand median 2.0000
FIGURE 13.9.1 MINITAB procedure and output for Example 13.9.1.
Computer Analysis Many statistics software packages, including MINITAB,
will perform the Friedman test. To use MINITAB we form three columns of data. We may,
for example, set up the columns so that Column 1 contains numbers that indicate the
treatment to which the observations belong, Column 2 contains numbers indicating the
blocks to which the observations belong, and Column 3 contains the observations. If we do
this for Example 13.9.1, the MINITAB procedure and output are as shown in Figure 13.9.1.
EXERCISES
For the following exercises perform the test at the indicated level of significance and determine the
p value.
13.9.1 The following table shows the scores made by nine randomly selected student nurses on final
examinations in three subject areas:
Subject Area
Student
Number Fundamentals Physiology Anatomy
1 98 95 77
2 95 71 79
(Continued)