Regionalized variable theory (RVT) is a geostatistical

Geostatistics

Geostatistics is a branch of statistics focusing on spatial or spatiotemporal datasets. Developed originally to predict probability distributions of ore grades for mining operations, it is currently applied in diverse disciplines including petroleum geology, hydrogeology, hydrology, meteorology,...

 method used for interpolation in space.

The concept of the theory is that interpolation from points in space should not be based on a smooth continuous object. It should be, however, based on a stochastic

Stochastic

Stochastic refers to systems whose behaviour is intrinsically non-deterministic. A stochastic process is one whose behavior is non-deterministic, in that a system's subsequent state is determined both by the process's predictable actions and by a random element. However, according to M. Kac and E...

 model that takes into consideration the various trends in the original set of points. The theory considers that within any dataset, three types of relationships can be detected:

1. Structural part, which is also called the trend.
2. Correlated variation.
3. Uncorrelated variation, or noise.

After defining the above three relationships, RVT then applies the first law of geography

First law of geography

The first law of geography according to Waldo Tobler is "Everything is related to everything else, but near things are more related than distant things."This observation is embedded in the gravity model of trip distribution...

, in order to predict the unknown values of points. The major application of this theory is the Kriging

Kriging

Kriging is a group of geostatistical techniques to interpolate the value of a random field at an unobserved location from observations of its value at nearby locations....

method for interpolation.