mxFitFunctionGREML {OpenMx} | R Documentation |
This function creates a new MxFitFunctionGREML
object.
mxFitFunctionGREML(dV=character(0), aug=character(0), augGrad=character(0), augHess=character(0))
dV |
Vector of character strings; defaults to a character vector of length zero. If a value of non-zero length is provided, it must be a named character vector. This vector's names must be the labels of each free parameter in the model. The vector's elements (i.e., the character strings themselves) must be the names of |
aug |
Character string; defaults to a character vector of length zero. Any elements after the first are ignored. The string should name a 1x1 |
augGrad |
Character string; defaults to a character vector of length zero. Any elements after the first are ignored. The string should name a |
augHess |
Character string; defaults to a character vector of length zero. Any elements after the first are ignored. The string should name a |
Making effective use of arguments dV
, augGrad
, and augHess
will usually require a custom mxComputeSequence()
. The derivatives of the REML loglikelihood function with respect to parameters can be internally computed from the derivatives of the 'V' matrix supplied via dV
. These loglikelihood derivatives will be valid as long as (1) the derivatives of 'V' evaluate to symmetric matrices the same size as 'V,' and (2) the model contains no MxConstraint
s. Internally, the derivatives of the 'V' matrix are assumed to be symmetric, and the elements above their main diagonals are ignored.
Currently, if any derivatives are provided via dV
, then derivatives must be provided for every free parameter in the MxModel.
Argument aug
is intended to allow users to provide penalty functions or prior likelihoods in order to approximate constraints or to regularize optimization. The user is warned that careless use of this augmentation feature may undermine the validity of his/her statistical inferences.
Returns a new object of class MxFitFunctionGREML
.
The OpenMx User's guide can be found at http://openmx.psyc.virginia.edu/documentation.
See MxFitFunctionGREML
for the S4 class created by mxFitFunctionGREML()
. For more information generally concerning GREML analyses, including a complete example, see mxExpectationGREML()
.
Other fit functions:
mxFitFunctionMultigroup
, mxFitFunctionML
,
mxFitFunctionWLS
, mxFitFunctionAlgebra
,
mxFitFunctionR
, mxFitFunctionRow
More information about the OpenMx package may be found here.
gff <- mxFitFunctionGREML() str(gff)