Coefficients for all possible sets of balanced orthogonal contrasts on a factor with 13 levels

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Coefficients for all possible sets of balanced orthogonal contrasts on a factor with 13 levels

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

slarregla@neiker.net

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Re: Coefficients for all possible sets of balanced orthogonal contrasts on a factor with 13 levels

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.

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Re: Coefficients for all possible sets of balanced orthogonal contrasts on a factor with 13 levels

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.

Steve Denham

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Re: Coefficients for all possible sets of balanced orthogonal contrasts on a factor with 13 levels

That's a good point, . Those higher order polynomials are probably meaningless.

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