  In order to analyze data on joint charged-particle/photon distributions from
an experimental search (T-864, MiniMax) for disoriented chiral condensate (DCC)
at the Fermilab Tevatron collider, we have identified robust observables,
ratios of normalized bivariate factorial moments, with many desirable
properties. These include insensitivity to many efficiency corrections and the
details of the modeling of the primary pion production, and sensitivity to the
production of DCC, as opposed to the generic, binomial-distribution partition
of pions into charged and neutral species. The relevant formalism is developed
and tested in Monte-Carlo simulations of the MiniMax experimental conditions.
