1\name{linesHyperb.lm}
2\alias{linesHyperb.lm}
3\title{Plot Confidence or Prediction Hyperbolas around a Regression Line}
4\description{
5  Add confidence/prediction hyperbolas for \eqn{y(x_0)}
6  to a plot with data or regression line.
7}
8\usage{
9linesHyperb.lm(object, c.prob=0.95, confidence=FALSE,
10            k=if (confidence) Inf else 1,
11            col=2, lty=2, do.abline=TRUE)
12}
13\arguments{
14  \item{object}{result of \code{\link{lm}(.)}.}
15  \item{c.prob}{coverage probability in \eqn{(0,1)}.}
16  \item{confidence}{logical; if true, do (small) confidence band, else,
17    realistic prediction band for the mean of \code{k} observations.}
18  \item{k}{integer or \code{Inf}; assume \code{k} future observations;
19    \code{k = Inf}  corresponds to confidence intervals (for y).}
20  \item{col, lty}{attributes for the \code{\link{lines}} to be drawn.}
21  \item{do.abline}{logical; if true, the regression line is drawn as well.}
22}
23\note{
24  With \code{\link{predict.lm}(*, interval=)} is available,
25  this function \code{linesHyperb.lm} is only slightly more general for
26  its \code{k} argument.
27}
28\author{Martin Maechler, Oct 1995}
29\seealso{\code{\link{predict.lm}(*, interval=)} optionally computes
30  prediction or confidence intervals.}
31\examples{
32data(swiss)
33      plot(Fertility ~ Education, data = swiss) # the data
34(lmS <- lm(Fertility ~ Education, data = swiss))
35linesHyperb.lm(lmS)
36linesHyperb.lm(lmS, conf=TRUE, col="blue")
37}
38\keyword{regression}
39\keyword{aplot}
40