My question may be simple. I tried to find a possible answer to my question, but failed to do so.

I am trying to construct a composite variable from multiple categorical variables. I want to get a single value (e.g., mean) from multiple categorical variables.
For instance, I want to estimate the effect of self-directed learning (SDL) on academic achievement. Both are categorical variables. There are five questions that are intended to assess the extent of SDL ability. So I would like to combine the five questions into one variable.

How can I do this in STATA?
egen, concat or egen, group are not what I am looking for because they do not give me a single value(number).
If they are continuous variables, egen, rowmean will work.

Or simply combining multiple categorical variables into a single variable is problematic, isn't it?
Please help me with this.