# McNemar-Bowker test for comparison of two measures

I am comparing two versions of a survey (an original, and a modified) and was wondering if the McNemar-Bowker test is appropriate.

The survey(s) ask respondents to indicate whether they've had an experience (in this case, unwanted sexual contact) since the age of 14. Respondents have four answer choices to indicate the frequency which they've had a certain experience, coded the following way:

  "never"
"once"
"twice"
"three or more times"


My hypothesis is that participants will indicate an increased number of experiences when given the modified version, as compared to the original. In this instance I am looking at the rates which men admit to having perpetrated acts of unwanted sexual contact; with the hypothesis that the modified version will ellicit increased rates of admitted perpetration compared to the original version.

My data do in fact show an increase in male admittal-rates on the modified version.

 MALE ORIGINAL     (n)                      MALE MODIFIED     (n)
"Never" =         281                      "Never" =         270
"Once" =           18                      "Once" =           18
"Twice" =           7                      "Twice" =           8
"Three +" =         7                      "Three +" =        17
Total admittal =  32                       Total admittal =  43
Total n =        313                       Total n =        313


So, now i want to test for significant difference between response rates on these two surveys to see if the increase of admittal on the modified version is statistically significantly higher. This is a repeated measures design, so each participant took both survey versions.

I am wondering if the McNemar-Bowker test is appropriate for my data (above)? My plan is to arrange the table as such:

                                 ORIGINAL SURVEY

|"Never" | "Once" | "Twice" | "Three +" | TOTAL |
|________|________|_________|___________|_______|
"Never"|  261   |   7    |    2    |     0     |  270  |
|________|________|_________|___________|_______|
"Once"|   12   |   5    |    1    |     0     |   18  |
|________|________|_________|___________|_______|
"Twice"|    3   |   4    |    1    |     0     |    8  |
|________|________|_________|___________|_______|
"Three +"|    5   |   2    |    3    |     7     |   17  |
|________|________|_________|___________|_______|
TOTAL |  281   |   18   |    7    |     7     |  313  |
|________|________|_________|___________|_______|


MODIFIED SURVEY

When I run the above analysis in SPSS crosstabs, I get a McNemar-Bowker chi-square value of 13.316, df = 6, p = 0.038. So my questions are:

1. Is the McNemar-Bowker appropriate for my data and hypothesis?
2. With the resulting p value of 0.038 can I now say that the results from the two surveys are significantly different -- with the modified version showing an increase in male admittal?