fit.nls {simex}R Documentation

Fits nls-models for the extrapolation step of SIMEX models

Description

Fits a nonlinear model of the form a+b/(c+lambda) to the data. Starting values are obtained by unsing quadratic extrapolation and an analytic way to obtain a three point fit to the model.

This function is for internal use only!

Usage

fit.nls(lambda, p.names, estimates)

Arguments

lambda vector of lambdas, for which the extrapolation should be made
p.names vector of variable names
estimates matrix of Simex estimates, as supplied by the functions simex

Details

Uses nls() with the obtained starting values as described by Carrol, Ruppert, Stefanski.

Value

a list of nls-objects, names are p.names

Note

numerical not stable, especially for constant functions

Author(s)

Wolfgang Lederer

See Also

simex, nls


[Package simex version 1.2 Index]