  In gravitational-wave data analysis, we regularly work with a host of
non-trivial prior probabilities on compact binary masses, redshifts, and spins.
We must regularly manipulate these priors, computing the implied priors on a
transformed basis of parameters or reweighting posterior samples from one prior
to another. Here, I detail some common manipulations, presenting a table of
Jacobians with which to transform priors between mass parametrizations,
describing the conversion between source- and detector-frame priors, and
deriving analytic expressions for priors on the "effective spin" parameters
regularly invoked in gravitational-wave astronomy.
