  One of the commonly used non-parametric morphometric statistics for galaxy
profiles and images is the asymmetry statistic. With an eye to current and
upcoming large neutral hydrogen (HI) surveys, we develop a 3D version of the
asymmetry statistic that can be applied to datacubes. This statistic is more
resilient to variations due to the observed geometry than 1D asymmetry
measures, and can be successfully applied to lower spatial resolutions (3-4
beams across the galaxy major axis) than the 2D statistic. We have also
modified the asymmetry definition from an `absolute difference' version to a
`squared difference' version that removes much of the bias due to noise
contributions for low signal-to-noise observations. Using a suite of mock
asymmetric cubes we show that the background-corrected, squared difference 3D
asymmetry statistic can be applied to many marginally resolved galaxies in
large wide-area HI surveys such as WALLABY on the Australian SKA Pathfinder
(ASKAP).
