If I have data such as
wage :
under 10K
10K - 20K
20K - 40K
40K - 80K
over 80K
don't know
rather not say
Which I wanted to use in a model, I don't think that I can use this as anything
other than an ordinal variable? It feels natural to want to be able to talk
about things in terms of wages increasing/decreasing, but as there are
categories of don't know
and rather not say
it seems that this is forced.
Looking at this post seems to support my thinking, but I wanted to check, perhaps there is some basic literature that might be recommended that covers this.