Dear Eileen, You apparently misunderstand what the effect() function does; it computes fitted values and their standard errors under the model (by default in a GLM on the scale of the response) at specific combinations of values of the predictors (e.g., letting two interacting predictors range over their combinations of values while others are held to their means). Details are provided in the references given in ?effect; see in particular the 2003 Journal of Statistical Software article at <http://www.jstatsoft.org/v08/i15>.
I hope this helps, John -------------------------------- John Fox Senator William McMaster Professor of Social Statistics Department of Sociology McMaster University Hamilton, Ontario, Canada http://socserv.mcmaster.ca/jfox > -----Original Message----- > From: r-help-boun...@r-project.org [mailto:r-help-bounces@r- > project.org] On Behalf Of Hlavka, Eileen > Sent: February-04-12 1:56 AM > To: r-help@r-project.org > Subject: [R] effect function (effects package) > > Dear all, > > How does the effect() function in the effects package calculate > effects and standard errors for glm quasipoisson models? I was using > effect() to calculate the impact of increasing x to e + epsilon, and > then finding the expected percent change. I thought that this effect > (as a percentage) should be exp(beta*epsilon), where beta is the > appropriate coefficient from the model, but that's not what I'm > getting using the effect() output. > > Sorry for the lack of example-it would require toy data etc. and seems > unnecessary since my question is more conceptual. > > Thanks, > > Eileen > > > > ______________________________________________________________________ > ____ > > This email message is for the sole use of the intended > r...{{dropped:9}} > > ______________________________________________ > R-help@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting- > guide.html > and provide commented, minimal, self-contained, reproducible code. ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
