What the HECK is a variogram?

One of the distinguishing characteristics of earth science datasets is their pattern of spatial continuity.

Two profiles of geological samples exhibiting completely different spatial continuity may produce the same universal statistical metrics, such as mean and standard deviation.

Therefore, a new type of statistics is invented to solve this problem.

One tool that belongs to this new type of statistics is correlogram,

  • A correlogram calculates the correlation between 2 points in space.
  • The correlation is a function of separation direction
  • The correlation may also be a function of distance
  • The separation vectors define both the separation direction and distance between sample pairs

The semi-variogram is simply the average squared distance from each point to the line x=y.