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Posts: 1

# Specify an error term

Hi all,

I am using proc GLM to analyze some data.  I want to specify the error term that is used to test certain factors.  In other words I don't want all the factors tested over the mean square error (MSE).  For example, imagine I have two factors A and B and their interaction A*B.  I would like to test A over A*B and B over A*B and then have A*B tested over the MSE.  I don't know how to specify the error term.  Can someone help?

Here's my code:

proc glm data=work.myexcel;

class A B;

model Y=A|B;

run;

Obviously if I do it like it is currently written A and B and A*B are tested over the MSE.  I'm not having much luck finding how to do this, but I know it can be done (and I'd imagine it's pretty easy to do).  I would appreciate any help anyone can give.  Thanks!!

P.S.  A and B are fixed factors, not rand if that matters at all.

Posts: 2,655

## Re: Specify an error term

You need to look at the TEST statement.

test h=A e=A*B;

test h=B e=A*B;

To answer your PS, yes it does matter if they are fixed or random.  However, when you state that the error term is A*B, you are explicitly calling a fixed effect a random effect.  If A and B are fixed, then I don't understand how A*B can be anything but fixed, and at this stage of things, I like my denominators in F tests to refer to something on the random side.  But that is just me.

Steve Denham

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