Sill of a semivariogram
= Sill of a semivariogram
The sill is the large-distance level of a <semivariogram> when that limit exists. For <covariance> tending to zero, the sill is the total marginal <variance>; a nugget plus a structured component has total sill $\tau^2+\sigma^2$. A nonzero constant <covariance> component is invisible to the <semivariogram>.