profile.nls {stats}R Documentation

Method for Profiling nls Objects


Investigates the profilelog-likelihood function for a fitted model of class "nls".


## S3 method for class 'nls':
profile(fitted, which = 1:npar, maxpts = 100, alphamax = 0.01,
        delta.t = cutoff/5, ...)


fitted the original fitted model object.
which the original model parameters which should be profiled. This can be a numeric or character vector. By default, all non-linear parameters are profiled.
maxpts maximum number of points to be used for profiling each parameter.
alphamax maximum significance level allowed for the profile t-statistics.
delta.t suggested change on the scale of the profile t-statistics. Default value chosen to allow profiling at about 10 parameter values.
... further arguments passed to or from other methods.


The profile t-statistics is defined as the square root of change in sum-of-squares divided by residual standard error with an appropriate sign.


A list with an element for each parameter being profiled. The elements are data-frames with two variables

par.vals a matrix of parameter values for each fitted model.
tau the profile t-statistics.


Of the original version, Douglas M. Bates and Saikat DebRoy


Bates, D. M. and Watts, D. G. (1988), Nonlinear Regression Analysis and Its Applications, Wiley (chapter 6).

See Also

nls, profile, plot.profile.nls


# obtain the fitted object
fm1 <- nls(demand ~ SSasympOrig( Time, A, lrc ), data = BOD)
# get the profile for the fitted model
pr1 <- profile( fm1 )
# profiled values for the two parameters

[Package stats version 2.5.0 Index]