Schematisation of a variogram. The points represent the measured data points (observed) and the curve represents the model function used (empirical). Range stands for the range sought, sill for the plateau value reached at maximum range, nugget for the nugget effect.
For example, in gold mining, a variogram will give a measure of how much two samples taken from the mining area will vary in gold percentage depending on the distance between those samples. Samples taken far apart will vary more than samples taken close to each other.
