I have what seemed like a straight-forward analysis to conduct, but perhaps is not. I have two trait categories or sets - behavior, physiology of birds - that I wish to understand the relationship between.
For the behavioral set I've measured three (somewhat related) variables, all quantitative. For the physiological set I've measured four (somewhat related) variables, all quantitative.
What options do I have for reducing each of these two sets to a [single] dimension so that I can correlate the two? The additional challenge is that I do not have a large sample size ($N=25$ individual birds).