  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.
