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Canonical correlation analysis (CCA)
¥To find relationships between two groups of variables, find pairs of linear functions of variables, one from each group, that have maximum correlation, subject to being uncorrelated with previously found pairs
¥Turns out to be another eigenvalue problem, involving covariance matrices between (Sxy) and within (Sxx, Syy) groups of variables
¥Solve SxySyy-1Syxakx=lkSxxakx   (akx = vector of loadings for x variables – similar equation for y variables)