  A significant challenge in zero-field muSR experiments arises from the
uncertainty in the muon site. It is possible to calculate the dipole field (and
hence precession frequency nu) at any particular site given the magnetic moment
mu and magnetic structure. One can also evaluate f(nu), the probability
distribution function of nu assuming that the muon site can be anywhere within
the unit cell with equal probability, excluding physically forbidden sites.
Since nu is obtained from experiment, what we would like to know is g(mu|nu),
the probability density function of mu given the observed nu. This can be
obtained from our calculated f(nu/mu) using Bayes' theorem. We describe an
approach to this problem which we have used to extract information about real
systems including a low-moment osmate compound, a family of molecular magnets,
and an iron-arsenide compound.
