¥All the techniques
discussed have an underlying objective of
dimension reduction and all use covariance or
correlation matrices. There is often a desire to
physically interpret the new dimensions –
this can be controversial
–For example,
oblique rotation is advocated by some because
Ôphysical modesÕ (NB different meaning of ÔmodeÕ)
are often correlated. Other techniques are advocated (independent component analysis – ICA; Aires et al., 2000) on the premise that ÔmodesÕ are not just uncorrelated, but independent