Let S = XTX be the sample covariance matrix where L and P are latent roots and vectors of XTX respectively. Prove that S has latent root and latent vectors P. Using this result show that correlation loadings of S are given by
where si is the ith diagonal element of S, and consequently correlation loadings are the same for both XTX and S. Show also that XTX and S possess the same standardized PC scores, but that unstandardized scores differ.