  When studying turbulence, it is often desirable to be able to estimate the
local spatial gradient of a vector quantity using in situ measurements from a
small number of irregularly spaced points. While previous studies have focused
on the accuracy of these methods as the number of measurement points varies, we
focus on the accuracy of gradient estimations as a function of shape of the
measurement point configuration. We find that for well-shaped configurations
that are of correct relative size, we can very accurately estimate the local
spatial gradient using only four points.
