Hi again I read the chapter and it says that I can nest B in A by writing A/B. But it doesnt seem to work properly. The package I use is pscl, I am trying to model zero inflated data. Here is the full model:
zip1<-zeroinfl(Visitation ~ Habitat/Site + Sps + TP + Resource + Sps*Habitat/Site + Sps*Resource + Sps*TP + TP*Resource + TP*Habitat/Site | TP + Sps + Resource + Habitat/Site + TP*Sps + Sps*Resource + TP*Resource + TP*Habitat/Site, data = data1) where as you can see I have tried to include Habitat/Site. But it doesnt seem like its possible to create interaction links that way. I would like create the interaction link between say Sps and Habitat/Site. If I write Sps*Habitat/Site R somehow thinks that its a 3-way interaction link and still includes habitat as a single variable. Here is the summary just so you can see: Count model coefficients (poisson with log link): Estimate Std. Error z value Pr(>|z|) (Intercept) 3.8643338 0.3450539 11.199 < 2e-16 *** Habitat -3.2757473 0.4871726 -6.724 1.77e-11 *** Sps -0.3332371 0.1117680 -2.982 0.00287 ** TP -0.3857513 0.0975556 -3.954 7.68e-05 *** Resource 0.0130935 0.0009545 13.717 < 2e-16 *** Habitat:Site 0.2487012 0.0415908 5.980 2.24e-09 *** Habitat:Sps 0.5432845 0.1230434 4.415 1.01e-05 *** Sps:Resource -0.0041420 0.0002632 -15.738 < 2e-16 *** Sps:TP 0.0438085 0.0189411 2.313 0.02073 * TP:Resource -0.0009413 0.0002887 -3.260 0.00111 ** Habitat:TP 0.1549435 0.1205884 1.285 0.19883 Habitat:Site:Sps -0.0305628 0.0107794 -2.835 0.00458 ** Habitat:Site:TP -0.0096408 0.0098497 -0.979 0.32768 Zero-inflation model coefficients (binomial with logit link): Estimate Std. Error z value Pr(>|z|) (Intercept) -1.3160850 0.8200631 -1.605 0.1085 TP 0.2808474 0.2657544 1.057 0.2906 Sps 0.8023648 0.1281520 6.261 3.82e-10 *** Resource -0.0075967 0.0035817 -2.121 0.0339 * Habitat -1.3122811 1.1348922 -1.156 0.2476 Habitat:Site 0.1390498 0.0984716 1.412 0.1579 TP:Sps -0.0189088 0.0406299 -0.465 0.6417 Sps:Resource -0.0005548 0.0006843 -0.811 0.4175 TP:Resource 0.0007100 0.0008454 0.840 0.4010 TP:Habitat 0.7195254 0.3666809 1.962 0.0497 * TP:Habitat:Site -0.0782610 0.0314229 -2.491 0.0128 * Thanks again Mark Difford wrote: > > Daniel, > >>> Yes I am trying to model such data, and i need R to know that Site is >>> nested within Habitat. >>> Do I use some kind of command before running the model (like factor() >>> and so on) or do i >>> write it in the model formula. If so, how? > > You still are not telling the list enough, since nesting specifications > are sometimes package/program specific. You could help yourself by reading > some of R's basic documentation about how to specify a nested model. Then > "it" will tell you what to do. > > ?formula > > Or read §11.1 of "An Introduction to R" (one of R's manuals). > > Regards, Mark. > > > DanielWC wrote: >> >> Hi. >> Yes I am trying to model such data, and i need R to know that Site is >> nested within Habitat. Do I use some kind of command before running the >> model (like factor() and so on) or do i write it in the model formula. If >> so, how? >> >> Thanks >> >> >> >> Douglas Bates-2 wrote: >>> >>> On Fri, May 29, 2009 at 7:50 AM, DanielWC <daniel.carsten...@gmail.com> >>> wrote: >>> >>>> Hello >>>> I am working with a biological data including variables called Habitat >>>> and >>>> Site, example: >>> >>>> Habitat Site >>> >>>> Forest Low >>>> Forest Low >>>> Forest High >>>> Forest High >>> >>>> I want to tell R that the Site variable is nested within the Forest >>>> variable >>>> (that it is not a new variable). >>>> Does anyone know how to do this? >>> >>> If you could explain what you mean by "tell R", it would help. Are >>> you trying to model such data and you want to know how to express the >>> relationship between such factors in a model formula? >>> >>> ______________________________________________ >>> 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. >>> >>> >> >> > > -- View this message in context: http://www.nabble.com/Nested-variables-tp23779402p23830019.html Sent from the R help mailing list archive at Nabble.com. ______________________________________________ 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.