.BG
.VE $Header: /usr3/s/current/s/.help/RCS/ppoints,v 1.2 83/12/30 19:32:28 rab Exp $
.FN ppoints
.TL
ppoints: Plotting Points for Q-Q Plots
.CS
ppoints(n)
.PP
.AG n
sample size for which plotting points desired (if `n' has
only 1 value) or data against which plot is to be made.
.PP
.RT
the vector of probabilities, `p', such that `qdist(p)'
plotted against `sort(y)' gives a probability (Q-Q) plot of
`y' against the distribution of which `qdist' is the
quantile function.  Computes `p[i]=(i\-.5)/n'
if `n>10' or `(i\-.375)/(n+.25)' otherwise.
.EX
plot(qlnorm(ppoints(y)),sort(y))   #log normal q-q plot
.KW basic*
.KW distribution
.KW probability
.KW quantile
.WR
