  We investigate the skewness of galaxy number density fluctuations as a
possible probe to test gravity theories. We find that the specific linear
combination of the skewness parameters corresponds to the coefficients of the
second-order kernels of the density contrast, which can be regarded as the
consistency relation and used as a test of general relativity and modified
gravity theories. We also extend the analysis of the skewness parameters from
real space to redshift space and derive the redshift-space skewness consistency
relation.
