Variogram.corRatio {nlme} R Documentation

## Calculate Semi-variogram for a corRatio Object

### Description

This method function calculates the semi-variogram values corresponding to the Rational Quadratic correlation model, using the estimated coefficients corresponding to `object`, at the distances defined by `distance`.

### Usage

```## S3 method for class 'corRatio':
Variogram(object, distance, sig2, length.out, ...)
```

### Arguments

 `object` an object inheriting from class `corRatio`, representing an Rational Quadratic spatial correlation structure. `distance` an optional numeric vector with the distances at which the semi-variogram is to be calculated. Defaults to `NULL`, in which case a sequence of length `length.out` between the minimum and maximum values of `getCovariate(object)` is used. `sig2` an optional numeric value representing the process variance. Defaults to `1`. `length.out` an optional integer specifying the length of the sequence of distances to be used for calculating the semi-variogram, when `distance = NULL`. Defaults to `50`. `...` 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

`corRatio`, `plot.Variogram`

### Examples

```cs1 <- corRatio(7, form = ~ Time | Rat)
cs1 <- Initialize(cs1, BodyWeight)
Variogram(cs1)[1:10,]
```

[Package nlme version 3.1-66 Index]