nlsBoot {nlstools}R Documentation

Bootstrap resampling

Description

Bootstrap resampling

Usage

nlsBoot (nls, niter = 999)
## S3 method for class 'nlsBoot':
plot (x, type = c("pairs", "boxplot"), 
        mfr = c(ceiling(sqrt(ncol(x$coefboot))), 
        ceiling(sqrt(ncol(x$coefboot)))), 
        ask = FALSE, ...)
## S3 method for class 'nlsBoot':
print (x, ...)
## S3 method for class 'nlsBoot':
summary (object, ...)

Arguments

nls an object of class 'nls'
niter number of iterations
x, object an object of class 'nlsBoot'
type type of representation (options are "pairs" or "boxplot")
mfr layout definition (number of rows and columns in the graphics device)
ask if TRUE, draw plot interactively
... further arguments passed to or from other methods

Details

Non-parametric bootstraping is used. Mean centered residuals are bootstraped. By default, 999 resampled data sets are created from which a bootstrap sample of estimates is built by fitting the model on each of these data sets. The function summary returns the bootstrap estimates and the 95 percent confidence intervals which are simply defined by the median and the 2.5 and 97.5 percentiles of the bootstrap sample of estimates. The bootstrap estimates distributions can be visualized using the function plot.nlsBoot either by plotting the bootstrap sample for each pair of parameters or by displaying the boxplot representation of the bootstrap sample for each parameter.

Value

nlsBoot returns a list of three objects:

coefboot contains the bootstrap parameter estimates
bootCI contains the bootstrap medians and the bootstrap 95% confidence intervals
rse is the vector of bootstrap residual errors

Author(s)

Florent Baty florent.baty@unibas.ch
Marie-Laure Delignette-Muller ml.delignette@vet-lyon.fr

References

Bates DM and Watts DG (1988) Nonlinear regression analysis and its applications. Wiley, Chichester, UK.

Huet S, Bouvier A, Poursat M-A, Jolivet E (2003) Statistical tools for nonlinear regression: a practical guide with S-PLUS and R examples. Springer, Berlin, Heidelberg, New York.

Examples

data(growthcurve)
bacterialKinetics <- growthcurve$df4
nls1 <- nls(gompertzm, bacterialKinetics, 
        list(lag = 10, mumax = 0.1, LOG10N0 = 6, LOG10Nmax = 9))
boo <- nlsBoot(nls1)
plot(boo)
plot(boo, type = "boxplot", ask=FALSE)
summary.nlsBoot(boo)
  

[Package nlstools version 0.0-5 Index]