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 )