CMB Cosmological Parameter Estimation: Methods and Current Results
  The majority of present efforts to constrain cosmological parameters with cosmic microwave background (CMB) anisotropy data employ approximate likelihood functions, the time consuming nature of a complete analysis being a major obstacle. We have performed a full (unapproximated) likelihood analysis on several experiments that allows us to examine the various assumptions made in these approximate methods and to evaluate their performance. Our results indicate that care should be taken when using such approaches. With an improved approximate method, we present some constraints on cosmological parameters using the entire present CMB data set. 
M. Douspis, J.G. Bartlett, A. Blanchard, M. Le Dour (Observatoire   Midi-Pyrenees, Toulouse France)