If it is not standardized, I have the following script that I use to calculate the r^2 for each variable of a model. I do wonder, however, if there is a way to calculate a model-wide r^2 like index.
-Jarrett ## #returns the r^2 for endogenous variables and error path coefficients # # Last updated 8/18/08 ## rsquare.sem<-function (sem.obj){ output.info<-list() for (index in 1:length(sem.obj$S[,1])){ var.name<-sem.obj$var.names[index] obs.var<-sem.obj$S[index,index] est.var<-sem.obj$P[index,index] r.sq<-1-(est.var/obs.var) std.error.coef<-sqrt(1-r.sq) #if it's 0, or close to (due to rounding error), it's exogenous if(r.sq > 1e-10){ output.info<-c(output.info, var.name, obs.var, est.var, r.sq, std.error.coef) } } output.matrix<-matrix(output.info, ncol=5, byrow=TRUE) colnames(output.matrix)<-c("Variable", "Observed.Variance", "Estimated.Variance", "R^2", "Standardized.Error.Coefficient") output.matrix } ---------------------------------------- Jarrett Byrnes Postdoctoral Associate, Santa Barbara Coastal LTER Marine Science Institute University of California Santa Barbara Santa Barbara, CA 93106-6150 http://www.lifesci.ucsb.edu/eemb/labs/cardinale/people/byrnes/index.html On Feb 9, 2010, at 4:17 AM, John Fox wrote: > Dear Kathryn, > > I assume that MWDError is the error variance associated with MWD. If > MWD is > a standardized variable (i.e., with a variance of 1) then 59% of its > variance is unaccounted for. > > I hope this helps, > John > > -------------------------------- > John Fox > Senator William McMaster > Professor of Social Statistics > Department of Sociology > McMaster University > Hamilton, Ontario, Canada > web: socserv.mcmaster.ca/jfox > >> -----Original Message----- >> From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org >> ] > On >> Behalf Of Kathryn Barto >> Sent: February-09-10 6:23 AM >> To: r-help@r-project.org >> Subject: [R] interpreting error estimate in SEM >> >> hi, >> >> I'm using the sem package, and I want to make sure I'm interpreting >> the >> output correctly. Here is an excerpt of my output. When I report >> the MWD >> error, should I say that 59% of the variation in MWD is not >> explained by > the >> model, or that 59% of the variation is explained, or something >> entirely >> different. >> >> Parameter Estimates >> Estimate Std Error z value Pr(>|z|) >> NplantRoots 0.462029 0.120803 3.82466 1.3095e-04 >> plantRoots > <-- >> - N >> ... >> CoError 1.000011 0.151850 6.58553 4.5325e-11 Co <--> Co >> carbonateError 1.000009 0.156217 6.40142 1.5394e-10 carbonate > <--> >> carbonate >> MWDError 0.589788 0.092128 6.40185 1.5351e-10 MWD >> <--> > MWD >> >> Thanks >> Kathryn >> >> ______________________________________________ >> 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. [[alternative HTML version deleted]] ______________________________________________ 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.