  Asymmetries in the neutral hydrogen gas distribution and kinematics of
galaxies are thought to be indicators for both gas accretion and gas removal
processes. These are of fundamental importance for galaxy formation and
evolution. Upcoming large blind HI surveys will provide tens of thousands of
galaxies for a study of these asymmetries in a proper statistical way. Due to
the large number of expected sources and the limited resolution of the majority
of objects, detailed modelling is not feasible for most detections. We need
fast, automatic and sensitive methods to classify these objects in an objective
way. Existing non-parametric methods suffer from effects like the dependence on
signal to noise, resolution and inclination. Here we show how to correctly take
these effects into account and show ways to estimate the precision of the
methods. We will use existing and modelled data to give an outlook on the
performance expected for galaxies observed in the various sky surveys planned
for e.g. WSRT/APERTIF and ASKAP.
