corClasses {nlme} | R Documentation |

## Correlation Structure Classes

### Description

Standard classes of correlation structures (`corStruct`

)
available in the `nlme`

package.

### Value

Available standard classes:

`corAR1` |
autoregressive process of order 1. |

`corARMA` |
autoregressive moving average process, with arbitrary orders for the autoregressive and moving average components. |

`corCAR1` |
continuous autoregressive process (AR(1) process for a continuous time covariate). |

`corCompSymm` |
compound symmetry structure corresponding to a constant correlation. |

`corExp` |
exponential spatial correlation. |

`corGaus` |
Gaussian spatial correlation. |

`corLin` |
linear spatial correlation. |

`corRatio` |
Rational quadratics spatial correlation. |

`corSpher` |
spherical spatial correlation. |

`corSymm` |
general correlation matrix, with no additional structure. |

### Note

Users may define their own `corStruct`

classes by specifying a
`constructor`

function and, at a minimum, methods for the
functions `corMatrix`

and `coef`

. For
examples of these functions, see the methods for classes `corSymm`

and `corAR1`

.

### Author(s)

JosÃ© Pinheiro and Douglas Bates bates@stat.wisc.edu

### References

Pinheiro, J.C., and Bates, D.M. (2000) "Mixed-Effects Models in S and S-PLUS", Springer.

### See Also

`corAR1`

, `corARMA`

,
`corCAR1`

, `corCompSymm`

,
`corExp`

, `corGaus`

,
`corLin`

,
`corRatio`

, `corSpher`

,
`corSymm`

,
`summary.corStruct`

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