  It is now common practice to constrain cosmological parameters using
supernovae (SNe) catalogues constructed from several different surveys. Before
performing such a joint analysis, however, one should check that parameter
constraints derived from the individual SNe surveys that make up the catalogue
are mutually consistent. We describe a statistically-robust mutual consistency
test, which we calibrate using simulations, and apply it to each pairwise
combination of the surveys making up, respectively, the UNION2 catalogue and
the very recent JLA compilation by Betoule et al. We find no inconsistencies in
the latter case, but conclusive evidence for inconsistency between some survey
pairs in the UNION2 catalogue.
