I have a question in a survey:
Q: Did you buy your product:
iii) By Telephone
I have asked this question to 255 respondents 6 months ago and 251 respondents the other day.
I would like to know how to test whether there is a significant difference in the way respondents answered this 6 months ago compared to the other day.
Having looked on the Internet for answers I think it's one of:
2 sample Z-Test for proportions
Independent-Samples Mann-Witney U Test
Chi Square Test (Although not all of the cells would have a sample size of >5 and I don't really want to compare hypothesised and observed data)
I would really appreciate any help in guiding to me to what the correct test to use is, and how I would do this in SPSS (v17.0 or v19.0).