contr.sdif {MASS} | R Documentation |
A coding for unordered factors based on successive differences.
contr.sdif(n, contrasts = TRUE)
n |
The number of levels required. |
contrasts |
Should there be n - 1 columns orthogonal to the mean (the default)
or n columns spanning the space.
|
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.
If contrasts is
TRUE
, a matrix with n
rows and n - 1
columns,
and the n
by n
identity matrix if contrasts
is FALSE
.
Venables, W. N. and Ripley, B. D. (2002) Modern Applied Statistics with S. Fourth Edition, Springer.
contr.treatment
, contr.sum
, contr.helmert
contr.sdif(6)