Semivariance
In spatial statistics, the empirical semivariance is described by
semivariance,where z is the attribute value
where z is a datum at a particular location, h is the distance between ordered data, and n is the number of paired data at a distance of h. The semivariance is half the variance of the increments, but the whole variance of z-values at given separation distance h.
A plot of semivariances versus distances between ordered data in a graph is known as a semivariogram rather than a variogram. Many authors call a variogram, others use the terms variogram and semivariogram synonymously. However, Bachmaier and Backes, who discussed this confusion, have shown that should be called a variogram, terms like semivariogram or semivariance should be avoided.
