

   QQuuaannttiillee--QQuuaannttiillee PPlloottss

        qqnorm(y, ylim, main = "Normal Q-Q Plot", xlab = "Theoretical Quantiles",
               ylab = "Sample Quantiles", ...)
        qqline(y, ...)
        qqplot(x, y, plot.it = TRUE, xlab = deparse(substitute(x)),
               ylab = deparse(substitute(y)), ...)

   DDeessccrriippttiioonn::

        `qqnorm' produces a normal QQ plot of the values in
        `y'.  `qqline' adds a line to a normal quantile-quan-
        tile plot which passes through the quartiles.

        Graphical parameters may be given as arguments to
        `qqnorm', `qqnorm' and `qqline'.

   SSeeee AAllssoo::

        `ppoints'.

   EExxaammpplleess::

        y <- rt(200, df = 5)
        qqnorm(y); qqline(y, col = 2)
        qqplot(y, rt(300, df = 5))
        data(precip)
        qqnorm(precip, ylab = "Precipitation [in/yr] for 70 US cities")

