logLik.drc {drc}

Extracting the log likelihood

Description

loglik extracts the value of the log likelihood function evaluated at the parameter estimates.

Usage

  ## S3 method for class 'drc'
logLik(object, ...)

Arguments

object

an object of class 'drc'.

...

additional arguments.

Value

The evaluated log likelihood as a numeric value and the corresponding degrees of freedom as well as the number of observations as attributes.

Note

The value of the log likelihood could be used to compare model fits of the same data based on different dose-response models or based on the same model but fitted different algorithms, software programmes, or starting values. For comparisons: Larger is better.

Author(s)

Christian Ritz

Examples

## Fitting a four-parameter log-logistic model
ryegrass.m1 <- drm(rootl ~conc, data = ryegrass, fct = LL.4()) 
logLik(ryegrass.m1)