Plot a profile.nls Object
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
"plot"(x, levels, conf = c(99, 95, 90, 80, 50)/100, absVal = TRUE, ylab = NULL, lty = 2, ...)
- an object of class
- levels, on the scale of the absolute value of a t
statistic, at which to interpolate intervals. Usually
confis used instead of giving
- a numeric vector of confidence levels for profile-based
confidence intervals on the parameters.
c(0.99, 0.95, 0.90, 0.80, 0.50).
- a logical value indicating whether or not the plots
should be on the scale of the absolute value of the profile t.
- the line type to be used for axis and dropped lines.
- ylab, ...
- other arguments to the
plot.defaultfunction can be passed here (but not
The plots are produced in a set of hard-coded colours, but as these
are coded by number their effect can be changed by setting the
palette. Colour 1 is used for the axes and 4 for the
profile itself. Colours 3 and 6 are used for the axis line at zero and
the horizontal/vertical lines dropping to the axes.
Bates, D.M. and Watts, D.G. (1988), Nonlinear Regression Analysis and Its Applications, Wiley (chapter 6)
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)