I have a set of data which contains answers to a questionnaire (questions about satisfaction rated 1 to 5) and some demographic information (sex, age). I can divide the data in two groups and I want to see if there is any statistical difference between those groups. I tried the Wilcoxon test, but I have many ties, so I'm not sure this is the test that I need. What would be the best test in this case?


1 Answer 1


two-sample Kolmogorov-Smirnov Test

  • $\begingroup$ The two-sample Kolmogorov-Smirnov does not deal with ties. If you ignore heavy ties you end up with a much lower significance level than desired, with corresponding impact on power. You would need to explain how to deal with ties. $\endgroup$
    – Glen_b
    Commented Apr 25, 2013 at 7:55
  • $\begingroup$ I'm interested in the issue with the ties, since by design there are going to be plenty of ties. There are 300-400 respondents and there are 5 answers to choose from. $\endgroup$
    – rslite
    Commented Apr 25, 2013 at 20:25
  • $\begingroup$ K-S test only works for continuous data, assuming that your CDF does not have jumps that mess up the asymptotic distribution. $\endgroup$
    – StasK
    Commented Jun 25, 2013 at 16:49

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