Question: Fwd: Re: 2x3 ANOVA

0

Denise Scholtens •

**70**wrote:
>Date: Thu, 15 Jul 2004 12:51:43 -0500
>To: "Jeff Lande" <land0038@umn.edu>
>From: Denise Scholtens <dscholtens@northwestern.edu>
>Subject: Re: [BioC] 2x3 ANOVA
>
>>
>>
>>Now, I'd like to start running some contrasts to see the effects at
>>particular graft type/day combinations (ie 14 day allografts) and
also
>>look at fold changes. I think both of these functions are possible
>>within the factDesign package, but I'm not sure how to input the
second
>>and the third parameters in the par2lambda function. If there's
anyone
>>who can give me some direction on this, I would greatly appreciate
it.
>
>Hi Jeff,
>
>par2lambda takes three coefficients - "betaNames", "betas", and
"coefs".
>
>"betaNames" refers to the names of the coefficients that are returned
with
>the lm, for example, you could do:
>
>betaNames <- names(lm.full[["coef"]])
>
>"betas" and "coefs" are used to define the specific contrasts of
>interest. The idea of the par2lambda function is not to have to
construct
>a contrast matrix by hand - if you did have to do this, you would
need to
>look at the order of the coefficients returned by the lm and make
sure
>your contrast matrix is specified accordingly. When performing many
>contrasts on several different factors, this can be a pain. In any
event,
>suppose your lm returns coefficients named "beta1", "beta2", "beta3",
and
>"beta4" and you want to test the contrast beta2 - beta4=0. Then you
would
>specify
>
>betas <- list(c("beta2","beta4"))
>coefs <- list(c(1,-1))
>
>and you're all set to use the par2lambda function. The list
structure is
>helpful if you want to simultaneously test two or more contrasts.
Suppose
>in addition to beta2-beta4=0, you want to test beta3+beta4=0. Then
you
>would say
>
>betas <- list(c("beta2","beta4"),c("beta3","beta4"))
>coefs <- list(c(1,-1),c(1,1))
>
>par2lambda(betaNames,betas,coefs) will then return the appropriate
>contrast matrix for use with contrastTest or findFC. There are
examples
>of how to specify these parameters in the documentation example for
the
>par2lambda function and also in the factDesign vignette.
>
>Hope this helps -
>Denise
>
>
>
>>
>>Thanks,
>>
>>Jeff Lande
>>Graduate Student - University of Minnesota
>>
>>
>> [[alternative HTML version deleted]]
>>
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>
>******************************************
>Denise Scholtens, Ph.D.
>Research Assistant Professor
>Northwestern Medical School
>Department of Preventive Medicine
>680 N. Lake Shore Drive Suite 1102
>Chicago, IL 60614
>phone: 312.503.7261
>fax: 312.908.9588
>dscholtens@northwestern.edu
******************************************
Denise Scholtens, Ph.D.
Research Assistant Professor
Northwestern Medical School
Department of Preventive Medicine
680 N. Lake Shore Drive Suite 1102
Chicago, IL 60614
phone: 312.503.7261
fax: 312.908.9588
dscholtens@northwestern.edu

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modified 15.4 years ago
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Jeff Lande •

**110**• written 15.4 years ago by Denise Scholtens •**70**