Displaying 2 results from an estimated 2 matches for "anocova".
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ancova
2011 Oct 17
1
Adjusted Means
I'm running the following ANCOVA model in R: X=a*b*d + d where d is the
covariate. I want to produce adjusted means for X for all possible
treatment combinations. a has 6 levels, b has 2 levels, c has 2 levels, so
this is a 6x2x2 = 24 possible treatment combinations. When I run:
effect("d", Ancova.Model) I am given only 20 adjusted means (also, I'm not
exactly sure of how the
2000 Aug 01
1
Testing for parallel slopes
...of simple bivariate linear regressions on grouped
data. I want to test the slopes to see if they are parallel. I normally
use analysis of covariance to do so, looking at interaction between the
covariate and the factor to make this determination.
VR3 pp.149 - 154 has a very nice example of an ANOCOVA, ending with a
discussion of this very operation.
My question has to do with the issue of parametrization. When I use the
example data set "whiteside", I get the same results that VR get (see p.
154) except I'm getting them *without* reparametrizing the model. (In fact,
I get th...