A new measure of tension between experiments
  Tensions between cosmological measurements by different surveys or probes
have always been important --- and are presently much discussed --- as they may
lead to evidence of new physics. Several tests have been devised to probe the
consistency of datasets given a cosmological model, but they often have
undesired features such as dependence on the prior volume, or burdensome
requirements such as that of near-Gaussian posterior distributions. We propose
a new quantity, defined in a similar way as the Bayesian evidence ratio, in
which these undesired properties are absent. We test the quantity on simple
models with Gaussian and non-Gaussian likelihoods. We then apply it to data
from the Planck satellite: we investigate the consistency of $\Lambda$CDM model
parameters obtained from TT and EE angular power spectrum measurements, as well
as the mutual consistency of cosmological parameters obtained from large scale
(multipoles, $\ell<1000$) and small scale ($\ell \geq 1000$) portions of each
measurement and find no significant discrepancy in the six-dimensional
$\Lambda$CDM parameter space.
