2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/147335We examine the problem of covariance belief revision using a geometric approach. We exhibit an inner-product space where covariance matrices live naturally --- a space of random real symmetric matrices. The inner-product on this space captures aspects of our beliefs about the relationship between covariance matrices of interest to us, providing a structure rich enough for us to adjust beliefs about unknown matrices in the light of data such as sample covariance matrices, exploiting second-order exchangeability specifications.To appear in the Bayesian Statistics 5 conference volume. LaTeX, 11 pages, Chicago BIB-style (included), 2 postscript figures. Also available as a postscript file from http://fourier.dur.ac.uk:8000/~dma3djw/djwgvar.html For information on [B/D], go to http://fourier.dur.ac.uk:8000/stats/bd/Data Analysis, Statistics and Probabilitytext