Why should I use McNemar's test?

McNemar's test determines whether paired proportions are different. For example, you can use McNemar's test to determine whether a training program changes the proportion of participants who answer a question correctly.

The following sample worksheet shows summarized data for 12 participants. The first row, Correct Before, shows that only 2 of the participants answered a specific test question correctly before training. Column C2, Correct After, shows that 9 participants answered the same question correctly after training. The training appears to increase the proportion of participants who answer the question correctly. A McNemar's test on these data yields a p-value of 0.039, which is significant at the 0.05 alpha level.

C1-T C2 C3
  Correct After Incorrect After
Correct Before 1 1
Incorrect Before 8 2

You can also enter data in raw form, as long as both columns contain exactly 2 unique values (see note below). The following table shows the same data from the table above entered in raw form. Each row indicates how one participant responded before and after the training.

C1-T C2-T
Before After
Incorrect Correct
Incorrect Correct
Incorrect Correct
Incorrect Correct
Incorrect Incorrect
Incorrect Correct
Correct Correct
Incorrect Incorrect
Correct Incorrect
Incorrect Correct
Incorrect Correct
Incorrect Correct
Note

Both columns of raw data must contain exactly 2 unique values. Otherwise, Minitab cannot know how to summarize the data into a 2-way table for the analysis. If one or both columns of raw data contain only 1 unique value, you should enter the data as a 2 x 2 table as shown in Table 1.

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