fit.nls: 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
Value
a list of nls-objects, names are p.names
Details
Uses nls() with the obtained starting values as described by Carrol, Ruppert, Stefanski.