R help - Feb 2013 - effect() error: non-conformable arguments

I am trying to calculate adjusted means according to a glm model with a
Poisson distribution using effect() in the 'effects' package. I've
done
this many times before with great success, but this time I'm getting an
error. My model contains two factors and two covariates/blocks and I would
like the adjusted mean and confidence intervals for each factor separately.
The model runs without errors as does Anova() and HSD.test() on the model,
but when I try to run effect("factor", model) I get the following
error:
Error in mod.matrix %*% V : non-conformable arguments

I understand that this error indicates that matrices are being created with
dimensions that can't be used in the calculations, or something to that
effect. But I don't understand enough about how the effect() function is
calculated to figure out where the problem is in my data. I checked my data
file for any NAs, missing values, etc. and can't find any problems. If
anyone has any suggestions for diagnostics or how to find the source of
this error I would greatly appreciate the help.

Thanks!

-- 
Elisha Sigmon
Ph.D. Candidate
The George Washington University
Department Of Biological Sciences
2023 G St. NW Suite 340
Washington, DC, USA 20052

	[[alternative HTML version deleted]]

Dear Elisha,

It's impossible to tell from the information that you provide what the
source of the problem is. The gold standard for a problem report is
"commented, minimal, self-contained, reproducible code" (quoting from
the
text at the bottom of all r-help postings) that would allow me to track down
the error, but you don't even show the model that you've fit. I suspect
that
there's something about the model that's incompatible with the effect()
function but what that might be is impossible to know from your message.

Please provide some more details and ideally a reproducible example.

Best,
 John

-----------------------------------------------
John Fox
Senator McMaster Professor of Social Statistics
Department of Sociology
McMaster University
Hamilton, Ontario, Canada


> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at
r-project.org]
> On Behalf Of Elisha Sigmon
> Sent: Thursday, February 07, 2013 2:57 PM
> To: r-help at r-project.org
> Subject: [R] effect() error: non-conformable arguments
> 
> I am trying to calculate adjusted means according to a glm model with a
> Poisson distribution using effect() in the 'effects' package.
I've done
> this many times before with great success, but this time I'm getting an
> error. My model contains two factors and two covariates/blocks and I
> would
> like the adjusted mean and confidence intervals for each factor
> separately.
> The model runs without errors as does Anova() and HSD.test() on the
> model,
> but when I try to run effect("factor", model) I get the following
error:
> Error in mod.matrix %*% V : non-conformable arguments
> 
> I understand that this error indicates that matrices are being created
> with
> dimensions that can't be used in the calculations, or something to that
> effect. But I don't understand enough about how the effect() function
is
> calculated to figure out where the problem is in my data. I checked my
> data
> file for any NAs, missing values, etc. and can't find any problems. If
> anyone has any suggestions for diagnostics or how to find the source of
> this error I would greatly appreciate the help.
> 
> Thanks!
> 
> --
> Elisha Sigmon
> Ph.D. Candidate
> The George Washington University
> Department Of Biological Sciences
> 2023 G St. NW Suite 340
> Washington, DC, USA 20052
> 
> 	[[alternative HTML version deleted]]
> 
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> PLEASE do read the posting guide http://www.R-project.org/posting-
> guide.html
> and provide commented, minimal, self-contained, reproducible code.