In spatial statistics, the empirical semivariance is described by semivariance, γ ( h ) = 1 2 n ( h ) ∑ i = 1 n ( h ) [ z ( x i + h ) − z ( x i ) ] 2 {\displaystyle \gamma (h)={\dfrac {1}{2n(h)}}\sum _{i=1}^{n(h)}[z(x_{i}+h)-z(x_{i})]^{2}} where z is the attribute value