plotnls: Plotting diagnostics for an 'nls' object

In statforbiology: Tools for Data Analyses in Biology

Plotting diagnostics for an nls object

Description

This function is aimed at providing some types of plots to assess the goodness of fit for the selected model. Three plots (selectable by the argument 'which') are currently available: a plot of residuals against fitted values (which = 1), a Normal Q-Q plot (which = 2) and a plot of predicted against expected (line) and observed (symbols). By default, type = 3 is provided. As for the third graph, we can either plot all the data (type= "all") or the group means (type = "means"; the default)

Usage

  plotnls(x, type = c("average", "all"),
                     xlim = NULL, gridsize = 100,
                     which = 3, ...)

Arguments

x	an object of class 'nls'
type	it can be either "means" or "all". In the first case, the group means are plotted for the third graph. It is only considered when which = 3
xlim	The limits for the x-axis (x1, x2)
gridsize	For 'which = 3', it sets the resolution of the fitted line
which	The type of graph: can be 1, 2 or 3 (see description). It defaults to 3.
...	additional graphical arguments

Details

It mimicks the behaviour of the function plot.lm()

Value

No return value, it produces a plot

Author(s)

Andrea Onofri

Examples

library(statforbiology)
degradation <- read.csv("https://www.casaonofri.it/_datasets/degradation.csv")
mod <- nls(Conc ~ A*exp(-k*Time),
               start=list(A=100, k=0.05),
               data=degradation)
plotnls(mod, which = 3)

statforbiology documentation built on Oct. 30, 2024, 9:13 a.m.