R: Number of model parameters

nParam.maxim {maxLik} | R Documentation

## Number of model parameters

### Description

This function returns the number of model parameters.

### Usage

    ## S3 method for class 'maxim'
    nParam(x, free=FALSE, ...)

### Arguments

`x` | a model returned by a maximisation method from the maxLik package.
`free` | logical, whether to report only the free parameters or the total number of parameters (default)
`...` | other arguments for methods

### Details

Free parameters are the parameters with no equality restrictions. Some parameters may be jointly restricted (e.g. sum of two probabilities equals unity). In this case the total number of parameters may depend on the normalization.

### Value

Number of parameters in the model

### Author(s)

Ott Toomet

### See Also

`nObs` for number of observations

### Examples

    ## fit a normal distribution by ML
    # generate a variable from normally distributed random numbers
    x <- rnorm( 100, 1, 2 )
    # log likelihood function (for individual observations)
    llf <- function( param ) {
       return( dnorm( x, mean = param[ 1 ], sd = param[ 2 ], log = TRUE ) )
    }
    ## ML method
    ml <- maxLik( llf, start = c( mu = 0, sigma = 1 ) )
    # return number of parameters
    nParam( ml )

[Package maxLik version 1.3-4 Index]