I have a matrix of observations for particular characteristics (5-point ratings).  These characteristics are organized into groups, but there aren't an equal number of characteristics in each group.

I'd like to calculate two types of correlations:

1) Correlation within groups (among characteristics): some measure of whether the characteristics within the group are measuring the same thing.


2) Correlation between groups: some measure, assuming that each group reflects one overall trait, of how each trait (group) is related to every other trait.

Does anybody have suggestions for where to start?

Thank you.