Seems easy enough to play around with, and need not be strictly numbers either, as long as rank is defined on your fields (they are sortable...total ordering? I'm rusty on my terminology). Basically sort X, take the variance of the rank of Y, Z, etc. Much in the same way you would compute multi variable correlation.
For example: Cor(X, Y & Z)
I know you could run them pairwise but itβs possible Cor(X, Y) and Cor(X, Z) are close to zero but Cor(X, Y & Z) is close to 1.