What is variogram in statistics?

What is variogram in statistics?

A variogram is a description of the spatial continuity of the data. The experimental variogram is a discrete function calculated using a measure of variability between pairs of points at various distances. The exact measure used depends on the variogram type selected (Deutsch & Journel 44-47).

How do you interpret a variogram?

A variogram value at a given h is the average squared difference between the values of the paired locations. If two locations, u and u + h, are close to each other in terms of the distance measurement, two values are similar, so the difference in their values, Z- Z, will be small.

What is the partial sill?

partial sill. [spatial statistics use for geostatistics] A parameter of a covariance or semivariogram model that represents the variance of a spatially autocorrelated process without any nugget effect. In the semivariogram model, the partial sill is the difference between the nugget and the sill.

What is nugget and sill in variogram?

SILL: The value at which the model first flattens out. RANGE: The distance at which the model first flattens out. NUGGET: The value at which the semi-variogram (almost) intercepts the y-value.

What is the purpose of a variogram?

A variogram is an effective tool for describing the behavior of non-stationary, spatial random processes. It is used primarily in spatial statistics, geostatistics, and statistical design; In geostatistics, it is an “essential step” for analyzing spatial variability (Gómez-Hernández et al., 1999).

What is directional variogram?

A directional variogram is a variogram where point pairs are only included into the semivariance calculation if they fulfill a specified spatial relation. This relation is expressed as a search area that identifies all directional points for a given specific point.

What is the difference between variogram and semi variogram?

As nouns the difference between variogram and semivariogram is that variogram is (statistics) a function of the spatial dependence of variance; a graph of this function while semivariogram is (statistics) a function of the spatial dependence of semivariance; a graph of this function.

What is sill nugget ratio?

The nugget-to-sill ratio (NSR) was used as a measure of the proportion of total observed variation that could not be explained by the observed spatial dependence of the variable.