Hi Dr. Grossman, The definition of fixed and random independent variables is really an eternal struggle. I believe the book of Tony Underwood might help you someway.
Underwood, A.J. Experiments in ecology: their logical design and interpretation using analysis of variance, xviii, 504p. Cambridge University Press, 1996. Best regards, Gabriel *Gabriel Barros Gonçalves de Souza* Biologist - M.Sc. in Ecology and Biomonitoring PhD Candidate in Ecology at Federal University of Rio de Janeiro (UFRJ) Laboratory of Fishery Biology and Technology CRBio: 59.707/05-D Cel: +55 (71) 99187-9065 CV Lattes: http://lattes.cnpq.br/4012374701934609 2016-05-17 15:12 GMT-03:00 Gary Grossman <gdgross...@gmail.com>: > I'm having a bit of difficulty getting a clear understanding of what > should be considered a fixed vs. a random effect in a linear mixed model > analysis of field data. Even the statisticians seem to say "it depends on > who's defining it" or "sometimes the same treatment/variable can be > either". Some examples may help, let's say I collected samples annually in > three sites and wanted to test for the effect of daily rainfall, daily > temperature, and density, on recruitment of individuals in the following > year. Using the lmer function in R which of these would be fixed effects > and which would be random? A reference or two would help. I really couldn't > find much in a google search on field studies, but I didn't go to anything > like zoological abstracts. TIA, g2 > > -- > Gary D. Grossman, PhD > Fellow, American Fisheries Soc. > > Professor of Animal Ecology > Warnell School of Forestry & Natural Resources > University of Georgia > Athens, GA, USA 30602 > > Website - Science, Art (G. Grossman Fine Art) and Music > www.garygrossman.net > > Board of Editors - Animal Biodiversity and Conservation > Editorial Board - Freshwater Biology > Editorial Board - Ecology Freshwater Fish > > Hutson Gallery Provincetown, MA - www.hutsongallery.net/artists.html > > >
