Hi I have not observed this problem and, as Stuart observed, generally see EMMs that differ from originals when covariates are involved. One thing to check might be whether it occurs with unequal ns per condition / cell? Could SPSS be estimating effects controlling for any confounding between factors?
If you have an example of this issue, I would be happy to see it. Take care Jim James M. Clark Professor of Psychology 204-786-9757 204-774-4134 Fax [email protected] >>> Stuart McKelvie <[email protected]> 14-Dec-11 12:38 PM >>> Dear Tipsters, I have puzzled over this question for a long time. When conducting an ANOPVA in SPSS, we have two options for obtaining means in each condition. 1. Click on descriptives. This gives means, standard deviations and sample sizes for all main effects and interactions. They appear at the beginning of the printout. 2. Under options, you can specify which means you want. This gives means and standard errors for the effects and interactions that you specify. They appear at the end of the printout. My question is: Why are these means sometimes different from the ones in the descriptives in 1? I think I have seen the term "estimated marginal means", with a reference to covariates, but if there are no covariates (it is ANOVA not ANCOVA), I do not understand this. I would have thought that a mean was a mean in ANOVA. Sincerely, Stuart ___________________________________________________________________________ "Floreat Labore" [cid:[email protected]] "Recti cultus pectora roborant" Stuart J. McKelvie, Ph.D., Phone: 819 822 9600 x 2402 Department of Psychology, Fax: 819 822 9661 Bishop's University, 2600 rue College, Sherbrooke, Québec J1M 1Z7, Canada. E-mail: [email protected]<mailto:[email protected]> (or [email protected]<mailto:[email protected]>) Bishop's University Psychology Department Web Page: http://www.ubishops.ca/ccc/div/soc/psy<blocked::http://www.ubishops.ca/ccc/div/soc/psy> Floreat Labore" [cid:[email protected]] [cid:[email protected]] ___________________________________________________________________________ --- You are currently subscribed to tips as: [email protected]. To unsubscribe click here: http://fsulist.frostburg.edu/u?id=13251.645f86b5cec4da0a56ffea7a891720c9&n=T&l=tips&o=14886 or send a blank email to leave-14886-13251.645f86b5cec4da0a56ffea7a89172...@fsulist.frostburg.edu --- You are currently subscribed to tips as: [email protected]. To unsubscribe click here: http://fsulist.frostburg.edu/u?id=13090.68da6e6e5325aa33287ff385b70df5d5&n=T&l=tips&o=14889 or send a blank email to leave-14889-13090.68da6e6e5325aa33287ff385b70df...@fsulist.frostburg.edu
