I was recently given a 4-option 17-item survey to analyze. The question about multidimensionality came up. I was given the raw file in SPSS and so decided I would start with the more common factor analysis of raw scores, then gradually move into how the Rasch model is more effective. I generated the Winsteps residual matrix and had SPSS run it. I then ran table 23 in Winsteps as a double check and compared the two data sets. What is odd is that for the first 3 of the 4 components, both data sets are virtually identical except that the loading signs seem randomly switched for various items. The 4th component is completely different. I've included the residual matrix I used, the SPSS syntax and the SPSS output. I selected PCA and no rotation, so I'm puzzled. I'm wondering where I went wrong. I've attached the Winsteps control and data file as well. I'd greatly appreciate any help you could provide.