contr.sdif

0th

Percentile

Successive Differences contrast coding

A coding for unordered factors based on successive differences.

Keywords
models
Usage
contr.sdif(n, contrasts = TRUE)
Arguments
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.
Details

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.

Value

  • If contrasts is TRUE, a matrix with n rows and n - 1 columns, and the n by n identity matrix if contrasts is FALSE.

References

Venables, W. N. and Ripley, B. D. (2002) Modern Applied Statistics with S. Fourth Edition, Springer.

See Also

contr.treatment, contr.sum, contr.helmert

Aliases
  • contr.sdif
Examples
contr.sdif(6)
Documentation reproduced from package MASS, version 7.3-0, License: GPL-2 | GPL-3

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