  In this paper we discuss a simple method of testing for the presence of
energy-dependent dispersion in high energy data-sets. It uses the minimisation
of the Kolmogorov distance between the cumulative distribution of two
probability functions as the statistical metric to estimate the magnitude of
any spectral dispersion within transient features in a light-curve and we also
show that it performs well in the presence of modest energy resolutions (~20%)
typical of gamma-ray observations. After presenting the method in detail we
apply it to a parameterised simulated lightcurve based on the extreme VHE
gamma-ray flare of PKS 2155-304 observed with H.E.S.S. in 2006, in order to
illustrate its potential through the concrete example of setting constraints on
quantum-gravity induced Lorentz invariance violation (LIV) effects. We obtain
comparable limits to those of the most advanced techniques used in LIV searches
applied to similar datasets, but the present method has the advantage of being
particularly straightforward to use. Whilst the development of the method was
motivated by LIV searches, it is also applicable to other astrophysical
situations where energy-dependent dispersion is expected, such as spectral lags
from the acceleration and cooling of particles in relativistic outflows.
