  The number of sigma of confidence in a determination of the neutrino mass
hierarchy may be obtained from the statistic Delta chi squared. However, as the
hierarchy is a discrete variable, this number is not given by the usual square
root formula. We review a simple Bayesian formula for the sensitivity to the
hierarchy that can be obtained from the median experiment as a function of
Delta chi squared. We compare this analytical formula to 6 years of simulated
data from JUNO together with a 4% (1%) determination of the effective
atmospheric mass splitting from the disappearance channel at MINOS (NOvA). We
find a Delta chi squared of 11 (20) yielding 2.6 sigma (3.9 sigma). However
when the unknown nonlinear energy response of the detector is included in our
analysis this significance degrades considerably. This degradation can be
eliminated by dividing the single detector into a near and far detector of the
same total target mass. A further advantage of a second detector is that, even
while the reactor neutrino experiment runs, the decay at rest of a single, high
intensity, continuously running pion source close to one of the detectors, such
as that described by the DAEdALUS project, may determine the leptonic
CP-violating phase delta.
