2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/11418We discuss the problems of applying Maximum Likelihood methods to the CMB and how one can make it both efficient and optimal. The solution is a generalised eigenvalue problem that allows virtually no loss of information about the parameter being estimated, but can allow a substantial compression of the data set. We discuss the more difficult question of simultaneous estimation of many parameters, and propose solutions. A much fuller account of most of this work is available (Tegmark, Taylor & Heavens 1997)5 pages (Latex), 6 postscript figures included, Published in Proceedings of the Particle Physics and Early Universe Conference (PPEUC), University of Cambridge, 7-11 April 1997Astrophysicstext