# corBlomberg

##### Blomberg et al.'s Correlation Structure

The ``ACDC'' (accelerated/decelerated) model assumes that continuous traits evolve under a Brownian motion model which rates accelerates (if \(g\) < 1) or decelerates (if \(g\) > 1) through time. If \(g\) = 1, then the model reduces to a Brownian motion model.

- Keywords
- models

##### Usage

```
corBlomberg(value, phy, form = ~1, fixed = FALSE)
# S3 method for corBlomberg
corMatrix(object, covariate = getCovariate(object),
corr = TRUE, ...)
# S3 method for corBlomberg
coef(object, unconstrained = TRUE, …)
```

##### Arguments

- value
the (initial) value of the parameter \(g\).

- phy
an object of class

`"phylo"`

.- form
(ignored).

- fixed
a logical specifying whether

`gls`

should estimate \(\gamma\) (the default) or keep it fixed.- object
an (initialized) object of class

`"corBlomberg"`

.- covariate
(ignored).

- corr
a logical value specifying whether to return the correlation matrix (the default) or the variance-covariance matrix.

- unconstrained
a logical value. If

`TRUE`

(the default), the coefficients are returned in unconstrained form (the same used in the optimization algorithm). If`FALSE`

the coefficients are returned in ``natural'', possibly constrained, form.- …
further arguments passed to or from other methods.

##### Value

an object of class `"corBlomberg"`

, the coefficients from an
object of this class, or the correlation matrix of an initialized
object of this class. In most situations, only `corBlomberg`

will
be called by the user.

##### References

Blomberg, S. P., Garland, Jr, T., and Ives, A. R. (2003) Testing for
phylogenetic signal in comparative data: behavioral traits are more
labile. *Evolution*, **57**, 717--745.

*Documentation reproduced from package ape, version 4.1, License: GPL (>= 2)*