The Semivariance reference article from the English Wikipedia on 24-Apr-2004
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Semivariance

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In spatial statistics, semivariance can be described by
where z is a data value at a particular location, h is the distance between data values, and n(h) counts the number of pairs of data values we are given, spaced a distance of h apart.

A plot of the semivariance versus distance between data values is known as a semivariogram, or simply as a variogram.

Relevant topics: geostatistics

References:

  1. Shine, J.A., Wakefield, G.I.: A comparison of supervised imagery classification using analyst-chosen and geostatistically-chosen training sets, 1999, http://www.geovista.psu.edu/sites/geocomp99/Gc99/044/gc_044.htm