plot.profile.nls {stats}

R Documentation

Plot a profile.nls Object

Description

Displays a series of plots of the profile t function and interpolated confidence intervals for the parameters in a nonlinear regression model that has been fit with nls and profiled with profile.nls.

Usage

## S3 method for class 'profile.nls'
plot(x, levels, conf= c(99, 95, 90, 80, 50)/100,
     absVal =TRUE, ...)

Arguments

x	an object of class "profile.nls"
levels	levels, on the scale of the absolute value of a t statistic, at which to interpolate intervals. Usually conf is used instead of giving levels explicitly.
conf	a numeric vector of confidence levels for profile-based confidence intervals on the parameters. Defaults to c(0.99, 0.95, 0.90, 0.80, 0.50).
absVal	a logical value indicating whether or not the plots should be on the scale of the absolute value of the profile t. Defaults to TRUE.
...	other arguments to the plot function can be passed here.

Author(s)

Douglas M. Bates and Saikat DebRoy

References

Bates, D.M. and Watts, D.G. (1988), Nonlinear Regression Analysis and Its Applications, Wiley (chapter 6)

See Also

nls, profile, profile.nls

Examples

require(graphics)

# obtain the fitted object
fm1 <- nls(demand ~ SSasympOrig(Time, A, lrc), data = BOD)
# get the profile for the fitted model
pr1 <- profile(fm1, alpha = 0.05)
opar <- par(mfrow = c(2,2), oma = c(1.1, 0, 1.1, 0), las = 1)
plot(pr1, conf = c(95, 90, 80, 50)/100)
plot(pr1, conf = c(95, 90, 80, 50)/100, absVal = FALSE)
mtext("Confidence intervals based on the profile sum of squares",
      side = 3, outer = TRUE)
mtext("BOD data - confidence levels of 50%, 80%, 90% and 95%",
      side = 1, outer = TRUE)
par(opar)

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