.BG
.VE $Header: /usr3/s/current/s/.help/RCS/qqplot,v 1.2 83/12/30 19:32:55 rab Exp $
.FN qqnorm
.FN qqplot
.TL
qqplot qqnorm: Quantile-Quantile Plots
.CS
qqplot(x, y, plot)
qqnorm(xy, datax, plot)
.PP
.AG x,y
vectors (not necesarily of the same length).  Each is taken
as a sample, for the `x' and `y' axis values of an empirical
probability plot.
.AG xy
vector of data for a normal probability plot.
.AG datax
logical flag, if TRUE, data goes on the `x' axis, if FALSE
(default) data goes on the `y' axis.
.AG plot
logical flag.  If `plot' is FALSE, these routines all return
a structure with components `x' and `y' which give the
coordinates of the points that would have been plotted.
Default is TRUE.
.PP
Graphical parameters may also be supplied as arguments to these
functions (see `par').
These functions can also take arguments `type' and `log'
to control plot type and logarithmic axes.
.RT
if `plot' is FALSE, a structure with components
`x' and `y' are returned, giving coordinates of the
points that would have been plotted.
.EX
zz<-qqplot(x,y,plot=F)      #save x and y coords of empirical qq
plot(zz)      #plot it
abline(rreg(zz$x,zz$y))  #fit robust line and draw it

# the example plot is produced by:
my.sample<-rt(50,5)
lab<-"50 samples from a t distribution with 5 d. f."
qqnorm(my.sample,main=lab,sub="QQ Plot with Normal")
.PI
.KW plot*
.KW hplot*
.KW probability
.KW distribution
.KW quantile
.KW dplot*
.WR
