  The Muon Ionization Cooling Experiment (MICE) will demonstrate the
feasibility of ionization cooling, the technique by which it is proposed to
cool the muon beam at a future neutrino factory or muon collider. The position
and momentum reconstruction of individual muons in the MICE trackers allows for
the development of alternative figures of merit in addition to beam emittance.
Contraction of the phase space volume occupied by a fraction of the sample, or
equivalently the increase in phase space density at its core, is an unequivocal
cooling signature. Single-particle amplitude and non-parametric statistics
provide reliable methods to estimate the phase space density function. These
techniques are robust to transmission losses and non-linearities, making them
optimally suited to perform a quantitative cooling measurement in MICE.
