I want to find the differences between three variables (all categorical). I have no controlled variables. Is there anybody who can send me a reference to run Generalized estimating equations (GEE) test in SPSS?
With regard to the interpretation of Generalized Estimating Equations I recommend the original article on GEE: Liang, K.Y. and S.L. Zeegr, Lomgitudinal data analysis using generalized linear models, Biometrika, 1986, 73, 13-22. You may also find much useful material related to GEE in chapter 9 of: McCullagh. P. and J.A. Nelder, Generalized Linear Models, second edition, 1989, Chapman and Hall.