05-10-2013 12:49 PM
Is there any procedure in SAS to create coefficients for all possible sets of balanced orthogonal contrasts on a factor with 13 levels?. Unfortunately, the program Contrasts.exe (http://www.southampton.ac.uk/~cpd/anovas/datasets/Orthogonal%20contrasts.htm) provides coefficients for all possible sets of balanced orthogonal contrasts on a factor with any number of levels up to a maximum of 12.
|Any helpful comments would be totally appreciative!||Thanks! Santiago|
05-10-2013 02:44 PM
I haven't tried this, so I'll leave this as an assignment for you
The article you link to says that the orthogonal contrasts are also called Helmert polynomials.
In PROC GLM, the repeated statement has a HELMERT option, see if that does what you want it to do.
05-14-2013 11:24 AM
Following up on 's reference to PROC GLM, also check out the POLYNOMIAL option, if you are looking for orthogonal polynomial contrasts (linear, quadratic, etc.), especially if your levels are unevenly spaced. Be wary of what is going on with those higher order polynomials, however. If you can distinguish between a ninth order polynomial and noise, I would like to see how it is done.