I want to describe the relationship between pairs of continuous variables. I know this is commonly done just by looking at a scatterplot, but I think this is not appropriate for my problem, because (1) my sample size is small (15), (2) I have a to do 28 comparisons, and (3) my goal is to have some certainty when describing a relationship, and make just a visual evaluation seems to me that is easy to make mistakes.
I am doing a research the relationship of soft and hard tissue in humans and simply stated my question is How is the relationship between soft and hard tissue? is it linear, exponential, etc? I appreciate if you could recommend me a test or a way to provide confident results on this matter