| probplot {e1071} | R Documentation |
Generates a probability plot for a ,specified theoretical
distributions, i.e., basically a
qqplot where the y-axis is labeled with
probabilities instead
of quantiles. The function
is mainly intended for teaching the concept of quantile plots.
probplot(x, qdist=qnorm, probs=NULL, line=TRUE,
xlab=NULL, ylab="Probability in %", ...)
## S3 method for class 'probplot':
lines(x, h=NULL, v=NULL, bend=FALSE, ...)
x |
A data vector for probplot, an object of class
probplot for the lines method. |
qdist |
A character string or a function for the quantiles of the target distribution. |
probs |
Vector of probabilities at which horizontal lines should be drawn. |
line |
Add a line passing through the quartiles to the plot? |
xlab, ylab |
Graphical parameters. |
h |
The y-value for a horizontal line. |
v |
The x-value for a vertical line. |
bend |
If TRUE, lines are ``bent'' at the quartile line, else
regular ablines are added. See examples. |
... |
Further arguments for qdist and graphical
parameters for lines. |
Friedrich Leisch
## a simple example
x <- rnorm(100, mean=5)
probplot(x)
## the same with horizontal tickmarks at the y-axis
opar <- par("las")
par(las=1)
probplot(x)
## this should show the lack of fit at the tails
probplot(x, "qunif")
## for increasing degrees of freedom the t-distribution converges to
## normal
probplot(x, qt, df=1)
probplot(x, qt, df=3)
probplot(x, qt, df=10)
probplot(x, qt, df=100)
## manually add the line through the quartiles
p <- probplot(x, line=FALSE)
lines(p, col="green", lty=2, lwd=2)
## Make the line at prob=0.5 red
lines(p, h=0.5, col="red")
### The following use the estimted distribution given by the green
### line:
## What is the probability that x is smaller than 7?
lines(p, v=7, bend=TRUE, col="blue")
## Median and 90% confidence interval
lines(p, h=.5, col="red", lwd=3, bend=TRUE)
lines(p, h=c(.05, .95), col="red", lwd=2, lty=3, bend=TRUE)
par(opar)