ci.plot

0th

Percentile

Plot confidence and prediction intervals for simple linear regression

The data, the least squares line, the confidence interval lines, and the prediction interval lines for a simple linear regression (lm(y ~ x)) are displayed. Tick marks are placed at the location of xbar, the x-value of the narrowest interval.

Keywords
regression, hplot
Usage
ci.plot(lm.object, ...)

# S3 method for lm ci.plot(lm.object, xlim=range(data[, x.name]), newdata, conf.level=.95, data=model.frame(lm.object), newfit, ylim, pch=19, lty=c(1,3,4,2), lwd=2, main.cex=1, main=list(paste(100*conf.level, "% confidence and prediction intervals for ", substitute(lm.object), sep=""), cex=main.cex), ... )

Arguments
lm.object

Linear model for one y and one x variable.

xlim

xlim for plot. Default is based on data from which lm.object was constructed.

newdata

data.frame containing data for which predictions are wanted. The variable name of the column must be identical to the name of the predictor variable in the model object. Defaults to a data.frame containing a vector spanning the range of observed data. User-specified values are appended to the default vector.

conf.level

Confidence level for intervals, defaults to .95

data

data extracted from the lm.object

newfit

Constructed data.frame containing the predictions,confidence interval, and prediction interval for the newdata.

ylim

ylim for plot. Default is based on the constructed prediction interval.

pch

Plotting character for observed points.

lty, lwd

Line types and line width for fit and intervals.

main.cex

Font size for main title.

main

Main title for plot

Additional arguments to be passed to panel function.

Value

"trellis" object containing the plot.

Note

The predict.lm functions in S-Plus and R differ. The S-Plus function can produce both confidence and prediction intervals with a single call. The R function produces only one of them in a single call. Therefore the default calculation of newfit within the function depends on the system.

See Also

lm, predict.lm

Aliases
  • ci.plot
  • ci.plot.lm
Examples
# NOT RUN {
tmp <- data.frame(x=rnorm(20), y=rnorm(20))
tmp.lm <- lm(y ~ x, data=tmp)
ci.plot(tmp.lm)
# }
Documentation reproduced from package HH, version 3.1-35, License: GPL (>= 2)

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