I've been trying to run some stats to check for correlation between an ordinal categories (such as body conditions classes) and a continuous variable (such as body measurements in cm). I'm really struggling to find a test that I can run that is suitable for this type of data. I have paired measurements from each individual entered in the spreadsheet.
Example hypothesis to test: Does a higher body condition index, tend to result in greater head length measurements?
I've tried: *Linear regression (but don't think this is appropriate given the x-axis variable is ordinal).
*Ordinal regression (but although the model fit is usually highly significant (<0.001), the data being analysed often seems to fail Pearsons goodness of fit test.
Multinominal regression (but Pearson's goodness of fit was highly significant (<0.001) so probably also not suitable to use.)
Principle coordinate analysis (but as I'm only using 2 variables this doesn't seem to be the correct test either).
I considered a spearman's rank order test, but that seems to require 2 ordinal values rather than just one.
I'm kind of out of ideas. Can anyone help please? (I know this should be easy, but I don't seem to be able to find a test that fits.) I've been using SPSS.
Thank you in advance.