Variogram.default {nlme} | R Documentation |

## Calculate Semi-variogram

### Description

This method function calculates the semi-variogram for an arbitrary
vector `object`

, according to the distances in `distance`

.
For each pair of elements *x,y* in `object`

, the
corresponding semi-variogram is *(x-y)^2/2*. The semi-variogram is
useful for identifying and modeling spatial correlation structures in
observations with constant expectation and constant variance.

### Usage

## Default S3 method:
Variogram(object, distance, ...)

### Arguments

`object` |
a numeric vector with the values to be used for
calculating the semi-variogram, usually a residual vector from a
fitted model. |

`distance` |
a numeric vector with the pairwise distances
corresponding to the elements of `object` . The order of the
elements in `distance` must correspond to the pairs
`(1,2), (1,3), ..., (n-1,n)` , with `n` representing the
length of `object` , and must have length `n(n-1)/2` . |

`...` |
some methods for this generic require additional
arguments. None are used in this method. |

### Value

a data frame with columns `variog`

and `dist`

representing,
respectively, the semi-variogram values and the corresponding
distances. The returned value inherits from class `Variogram`

.

### Author(s)

Jose Pinheiro Jose.Pinheiro@pharma.novartis.com and Douglas Bates bates@stat.wisc.edu

### References

Cressie, N.A.C. (1993), "Statistics for Spatial Data", J. Wiley & Sons.

### See Also

`Variogram.gls`

, `Variogram.lme`

,
`plot.Variogram`

### Examples

## Not run:
fm1 <- lm(follicles ~ sin(2 * pi * Time) + cos(2 * pi * Time), Ovary,
subset = Mare == 1)
Variogram(resid(fm1), dist(1:29))[1:10,]
## End(Not run)

[Package

*nlme* version 3.1-57

Index]