qq {lattice}  R Documentation 
QuantileQuantile plots for comparing two Distributions
qq(formula, f.value = NULL, ...)
formula 
formula of the form y ~ x  g1 * g2 * ... ,
where x must be a numeric, and y can be a factor,
shingle, character or numeric vector, with the restriction that there
must be exactly two levels of y , which divide the values of
x into two groups. Quantiles for these groups will be plotted
along the two axes.

f.value 
optional function of a single integer (representing
the larger of the two sample sizes), returning a vector of
probabilities corresponding to which quantiles should be
plotted. The typical value for this argument is ppoints ,
which is also the SPLUS default. If specified, the probabilities
generated by this function is used for the plotted quantiles, using
the quantile function.
f.value defaults to NULL , which is equivalent to
using function(n) ppoints(n, a = 1) . This has the effect of
including the minimum and maximum data values in the computed
quantiles. This is similar to what happens for qqplot but
different from the default qq behaviour in SPLUS.

... 
Other arguments 
qq
produces a QQ plot of two samples. The default behaviour
of qq
is different from the corresponding SPLUS function. See
the entry for f.value
for specifics.
This and all other high level Trellis functions have several
arguments in common. These are extensively documented only in the
help page for xyplot
, which should be consulted to learn more
detailed usage.
An object of class ``trellis''. The `update' method can be used to update components of the object and the `print' method (usually called by default) will plot it on an appropriate plotting device.
Deepayan Sarkar Deepayan.Sarkar@Rproject.org
xyplot
, panel.qq
,
qqmath
, Lattice
qq(voice.part ~ height, aspect = 1, data = singer, subset = (voice.part == "Bass 2"  voice.part == "Tenor 1"))