variance
Computes the variance of all observations.
Returns Double.NaN if there are fewer observations than required (at least 2 for PopulationKind.SAMPLE, at least 1 for PopulationKind.POPULATION).
Return
the variance, or Double.NaN if insufficient data.
Parameters
kind
whether to compute sample variance (divides by n-1) or population variance (divides by n). Defaults to PopulationKind.SAMPLE.