Hi Dylan,
Am I trying to use contrast.Design() for something that it was not
intended for? ...
I think Prof. Harrell's main point had to do with how interactions are
handled. You can also get the kind of contrasts that Patrick was interested
in via multcomp. If we do this using your
On 2/16/2009 10:18 PM, Dylan Beaudette wrote:
On Mon, Feb 16, 2009 at 5:28 PM, Patrick Giraudoux
patrick.giraud...@univ-fcomte.fr wrote:
Greg Snow a écrit :
One approach is to create your own contrasts matrix:
mycmat - diag(8)
mycmat[ row(mycmat) == col(mycmat) + 1 ] - -1
mycmati -
Hi Dylan, Chuck,
contrast(l, a=list(f=levels(d$f)[1:3], x=0), b=list(f=levels(d$f)[4],
x=0))
There is a subtlety here that needs to be emphasized. Setting the
interacting variable (x) to zero is reasonable in this case, because the
mean value of rnorm(n) is zero. However, in the real world
Hi Dylan, Chuck,
Mark Difford wrote:
Coming to your question [?] about how to generate the kind of contrasts
that Patrick wanted
using contrast.Design. Well, it is not that straightforward, though I may
have missed
something in the documentation to the function. In the past I have
Dear listers,
I would like to compare the levels of a factor with 8 age categories
(0,10] (10,20] (20,30] (30,40] (40,50] (50,60] (60,70] (70,90] (however,
the factor has not been ordered yet). The default in glm is
cont.treatment (for unordered factors) and that leads to compare each
level to
of age categories using contrasts
Dear listers,
I would like to compare the levels of a factor with 8 age categories
(0,10] (10,20] (20,30] (30,40] (40,50] (50,60] (60,70] (70,90]
(however,
the factor has not been ordered yet). The default in glm is
cont.treatment (for unordered factors
Greg Snow a écrit :
One approach is to create your own contrasts matrix:
mycmat - diag(8)
mycmat[ row(mycmat) == col(mycmat) + 1 ] - -1
mycmati - solve(mycmat)
contrasts(agefactor) - mycmati[,-1]
Now when you use agefactor, the intercept will be the first age group and the
On Mon, Feb 16, 2009 at 5:28 PM, Patrick Giraudoux
patrick.giraud...@univ-fcomte.fr wrote:
Greg Snow a écrit :
One approach is to create your own contrasts matrix:
mycmat - diag(8)
mycmat[ row(mycmat) == col(mycmat) + 1 ] - -1
mycmati - solve(mycmat)
contrasts(agefactor) - mycmati[,-1]
Dear listers,
I would like to compare the levels of a factor with 8 age categories
(0,10] (10,20] (20,30] (30,40] (40,50] (50,60] (60,70] (70,90] (however,
the factor has not been ordered yet). The default in glm is
cont.treatment (for unordered factors) and that leads to compare each
level
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