Re: fixed effect with ancova

Posted by David Marso on Aug 23, 2011; 2:38pm
URL: http://spssx-discussion.165.s1.nabble.com/fixed-effect-with-ancova-tp4713723p4727002.html

ro wrote

Hi all,

IMNSHO,
Using Length as a "Covariate" in this case is *WRONG*.  It is correlated with the treatments (diet).
I should think of this perhaps as a Bivariate response (use both weight and length as dependent variables).
OTOH, I don't know WTF I am talking about...Sounds like the OP is fishing!!!
HTH, David

Gene, Longcms is the lenght, this was the variate that have good correlation with weight, in a GLM analysis i can add a covariate...for me this is an ancova analysis, i am right?...

my data was checked twice for 2 different people, but iam gonna review again...

Art, i plot data and lines are not parallel, interaction exist!, but i am not agree with a point (mean), i will check again.

anyway, can i add interaction to a lineal model (remember that i am try to find the best lineal model that adjust to my data), i only thought that fixed effects and covariates are main effects to my model...

Thanks Gene, Rich and Art for you support and you spend time, i will check all data (previously was checked but i am gonna do again with original data...).
any news i ll stay in touch...