rstudents: Studentized Residuals from a Nonlinear Model

In genomaths/usefr: Utility Functions for Statistical Analyses

Studentized Residuals from a Nonlinear Model

Description

Given a fitted model and additional information, this function computes the corresponding internally studentized residuals.

Usage

rstudents(model, varobj, method = c("Richardson", "simple", "complex"), ...)

## S4 method for signature 'missingORNULL'
rstudents(
  model,
  varobj,
  method = c("Richardson", "simple", "complex"),
  pars,
  fun,
  residuals
)

## S4 method for signature 'nls'
rstudents(
  model,
  varobj,
  method = c("Richardson", "simple", "complex"),
  residuals = NULL
)

## S4 method for signature 'CDFmodel'
rstudents(
  model,
  varobj,
  method = c("Richardson", "simple", "complex"),
  residuals = NULL
)

## S4 method for signature 'nls.lm'
rstudents(
  model,
  varobj,
  method = c("Richardson", "simple", "complex"),
  fun,
  residuals = NULL
)

Arguments

model	An object from the ""nls" class. It can be derived. e.g., from function nls or nlsLM from the R packages stats and minpack.lm, respectively.
varobj	Objective variable used build the model.
method	Argument for grad function from numDeriv package. One of "Richardson", "simple", or "complex" indicating the method to use for the approximation.
pars	model parameters.
fun	The named expression (not a character string) of the fitted model. For example, the normal distribution function is given by pnorm (see ?pnorm).
residuals	Residuals from the model fitting.

Details

If the model argument is provided, then only the argument varobj are required. The internally studentized residuals are computed as t = residuals/(s * sqrt(1 - h)), where h is the diagonal of the hat matrix and s is the estimation of the residual variation ((see Wikipedia)).

If the hat matrix cannot be estimated, the standardized residual are estimated as equal to the value of a residual, divided by an estimation of its standard deviation, i.e., t = residuals/s.

Studentized/Standardized residuals greater than 2 and less than -2 are usually considered large.

Value

A vector of studentized residuals when model is missing, NULL, or "nls" class object. If model="CDFmodel, then it will update the information carried on model$rstudent and the model will be returned.

genomaths/usefr documentation built on April 18, 2023, 3:35 a.m.