contr.sdif(n, contrasts = T)
n - 1
columns orthogonal to the mean (the default)
or
n
columns spanning the space.
contrasts is
TRUE
, a matrix with
n
rows and
n - 1
columns,
and the
n
by
n
identity matrix if
contrasts
is
FALSE
.
The contrast coefficients are chosen so that the coded coefficients in a one-way layout are the differences between the means of the second and first levels, the third and second levels, and so on.
Venables, W. N. and Ripley, B. D. (2002) Modern Applied Statistics with S. Fourth Edition, Springer.
contr.sdif(6)