corresp(x, nf = 1, ...)
"crosstabs"
and formulae of the form
~ F1 + F2
, where
F1
and
F2
are factors.
"correspondence"
for which
print
,
plot
and
biplot
methods are supplied. The main
components are the canonical correlation(s) and the row and column
scores.
See the reference. The
plot
method
produces a graphical representation of the table if
nf=1
, with the areas of circles
representing the numbers of points. If
nf
is two or more the
biplot
method is called, which plots the
second and third columns of the matrices
A = Dr^(-1/2) U
L
and
B = Dc^(-1/2) V L
where the singular value decomposition is
U L
V
. Thus the x-axis is the canonical correlation times
the row and column scores. Although this is called a biplot, it does
not have any useful inner product relationship between the
row and column scores. Think of this as an equally-scaled plot with
two unrelated sets of labels. The origin is marked on the plot with a
cross. (For other versions of this plot see the book.)
Venables & Ripley (2002), chapter 11.
ct <- corresp(~ Age + Eth, data = quine) ct plot(ct) corresp(caith) biplot(corresp(caith, nf = 2))