# Parameters in mmds

### Description

The internal parametrisation used in `mmds`

is not
directly interpretable. This man page aims to explain how
to interpret the parameters and transform them into
useful information.

### Details

Parametrisation works differently for the scale parameters of the half-normals and for the mixture proportions.

The scale parameters of the half-normals (or their constituent parameters in the case of a covariate model) are given on the log scale.

The mixture proportions are transformed to a parametrisation that allows values to lie over all of the real line (see Miller and Thomas for details).

The parameter vector is made up of the scale parameters
followed by the mixture parameters. In the non-covariate
case the former is the length of the number of mixtures
(`mix.terms`

) and the latter is of length
`mix.terms`

-1. When the model has covariates the
scale paramters are given as `mix.terms`

intercepts
followed by the covariate parameters.

The function `getpars`

transforms the
parameters (`$pars`

element) in a
`ds.mixture`

object to a named list.

Calling `summary.ds.mixture`

will show the
mixture proportions.

The parameter `initialvalues`

supplied to
`fitmix`

.

### Author(s)

David L. Miller