predict.nls
Predicting from Nonlinear Least Squares Fits
predict.nls produces predicted values, obtained by evaluating
the regression function in the frame newdata. If the logical
se.fit is TRUE, standard errors of the predictions are
calculated. If the numeric argument scale is set (with
optional df), it is used as the residual standard deviation in
the computation of the standard errors, otherwise this is extracted
from the model fit. Setting intervals specifies computation of
confidence or prediction (tolerance) intervals at the specified
level.
At present se.fit and interval are ignored.
- Keywords
- models, regression, nonlinear
Usage
# S3 method for nls
predict(object, newdata , se.fit = FALSE, scale = NULL, df = Inf,
interval = c("none", "confidence", "prediction"),
level = 0.95, …)Arguments
- object
An object that inherits from class
nls.- newdata
A named list or data frame in which to look for variables with which to predict. If
newdatais missing the fitted values at the original data points are returned.- se.fit
A logical value indicating if the standard errors of the predictions should be calculated. Defaults to
FALSE. At present this argument is ignored.- scale
A numeric scalar. If it is set (with optional
df), it is used as the residual standard deviation in the computation of the standard errors, otherwise this information is extracted from the model fit. At present this argument is ignored.- df
A positive numeric scalar giving the number of degrees of freedom for the
scaleestimate. At present this argument is ignored.- interval
A character string indicating if prediction intervals or a confidence interval on the mean responses are to be calculated. At present this argument is ignored.
- level
A numeric scalar between 0 and 1 giving the confidence level for the intervals (if any) to be calculated. At present this argument is ignored.
- …
Additional optional arguments. At present no optional arguments are used.
Value
predict.nls produces a vector of predictions.
When implemented, interval will produce a matrix of
predictions and bounds with column names fit, lwr, and
upr. When implemented, if se.fit is
TRUE, a list with the following components will be returned:
vector or matrix as above
standard error of predictions
residual standard deviations
degrees of freedom for residual
Note
Variables are first looked for in newdata and then searched for
in the usual way (which will include the environment of the formula
used in the fit). A warning will be given if the
variables found are not of the same length as those in newdata
if it was supplied.
See Also
Examples
library(stats)
# NOT RUN {
require(graphics)
fm <- nls(demand ~ SSasympOrig(Time, A, lrc), data = BOD)
predict(fm) # fitted values at observed times
## Form data plot and smooth line for the predictions
opar <- par(las = 1)
plot(demand ~ Time, data = BOD, col = 4,
main = "BOD data and fitted first-order curve",
xlim = c(0,7), ylim = c(0, 20) )
tt <- seq(0, 8, length = 101)
lines(tt, predict(fm, list(Time = tt)))
par(opar)
# }