[R] forcing a zero level in contr.sum

Bond, Stephen
2010-07-07T19:13:43Z

I need to use contr.sum and observe that some levels are not statistically
different from the overall mean of zero.
What is the proper way of forcing the zero estimate? It seems the column
corresponding to that level should become a column of zeros.
Is there a way to achieve that without me constructing the design matrix?
Thank you.

Stephen Bond


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