Dear Michael,
>From ?effect (under "Warnings and Limitations"):
"Binomial generalized linear models cannot have a matrix of successes and
failures on the left-hand side of the model formula; instead specify the
proportion of successes (i.e., successes/(successes + failures)) as the
response, and give the number of binomial trials (i.e., successes + failures) in
the weights argument to glm."
Best,
John
------------------------------------------------
John Fox
Sen. William McMaster Prof. of Social Statistics
Department of Sociology
McMaster University
Hamilton, Ontario, Canada
http://socserv.mcmaster.ca/jfox/
On Wed, 11 Apr 2012 07:20:51 -0400
Michael Kubovy <kubovy at virginia.edu> wrote:> > sessionInfo()
> R version 2.15.0 (2012-03-30)
> Platform: x86_64-apple-darwin9.8.0/x86_64 (64-bit)
>
> locale:
> [1] en_US.UTF-8/en_US.UTF-8/en_US.UTF-8/C/en_US.UTF-8/en_US.UTF-8
>
> attached base packages:
> [1] grid datasets splines utils stats
> [6] graphics grDevices methods base
>
> other attached packages:
> [1] effects_2.1-0 colorspace_1.1-1
> [3] nnet_7.3-1 nlme_3.1-103
> [5] lattice_0.20-6 reshape_0.8.4
> [7] plyr_1.7.1 catdata_1.0
> [9] cacheSweave_0.6-1 stashR_0.3-5
> [11] filehash_2.2-1 BiocInstaller_1.4.3
> [13] ctv_0.7-4 sos_1.3-1
> [15] brew_1.0-6 Hmisc_3.9-3
> [17] survival_2.36-12 MASS_7.3-17
>
> loaded via a namespace (and not attached):
> [1] cluster_1.14.2 digest_0.5.2 tools_2.15.0
>
> # copy and paste the following:
> library( catdata )
> data( unemployment )
> unempt <- unemployment
> unempt$durbin <- unempt$durbin - 1
> library( reshape )
> unempt <- melt( table( unempt ) )
> unempw <- cast( unempt, age ~ durbin )
> names( unempw ) <- c( 'age', 'short', 'long' )
> modt <- glm( durbin ~ age, weights = value, family = binomial, data =
unempt )
> modw <- glm( cbind( short, long ) ~ age, family = binomial, data =
unempw )
> library( effects )
> modt.ef <- effect( 'age', modt ) # works!
> modw.ef <- effect( 'age', modw ) # doesn't work!
> # Error in eval(expr, envir, enclos) : object 'age' not found
> # end
>
> ______________________________________________
> Professor Michael Kubovy
> University of Virginia
> Department of Psychology
> for mail add: for FedEx or UPS add:
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> Charlottesville, VA 22904-4400 485 McCormick Road
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> room phone
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> WWW: http://www.people.virginia.edu/~mk9y/
>