Sample variance of the higher-order cumulants of the cosmic velocity divergence field

If primordial fluctuations follow Gaussian distribution, higher-order cumul ants of cosmic fields could reflect nonlinear mode coupling, and would prov ide useful information about the gravitational instability picture of struc ture formation. We show that, in the usual case that the observed sample ha s a limited volume, their expected deviation (sample variance) from their u niversal values is nonvanishing, even in linear theory. As a result, we fin d that the relative sample variance of the skewness of the velocity diverge nce field can be as large as similar to 30% in current velocity surveys.