I have some questions regarding the usage of CATPCA in SPSS. I hope the answers to these questions will be helpful for others too who are planning to work on it.
1) In my data (on this data I want to run a CATPCA), there are some variables that are in proportions. But CATPCA treats the values with less than 1 as missing. So, I was planning to recode the scale variables that are in proportions into 10 categories (i.e. 0.00-0.10, 0.10-0.20, ..., 0.90-1.00). If I do this, then which optimal scaling level should I choose? Ordinal?
2) Other than the variables that are in proportions, the variables are categorical (both yes-no type and ordinal) with maximum 4 categories. So, if I split the proportion-type variables into 10 categories, will that be any problem? Or, do you think I should split them into 5 categories (i.e. 0.00-0.20, 0.20-0.40, ..., 0.80-1.00)?
3) My yes-no type variables are coded as 0-1. To avoid treating 0 as missing, I am planning to recode them as 1-2. Now, for my study, 'yes' means good and 'no' means bad/not good. So, which optimal scaling level should I choose for them? Ordinal or Nominal?
4) What to do if the same quantification comes for different categories of an ordinal variable? Should we merge the categories or use different optimal scaling level?
5) I had actually 4 factors associated with the questionnaire. So, I guess I should use 4 dimensions in solution. But how can I visualize the grouping of the variables (loadings plot) with this 4 dimensions? I actually need to know which dimension belongs to which factor. How do I check this?
6) When do we use 'multiple nominal' as the optimal scaling level? Any example?