On Jul 25, 2012, at 14:56 , arun wrote: > Hi, > > From the ANOVA results, you could get MSE and MS of group. MSE is basically > sigma^2 error. MS group of MS between group contains sigma^2 > error+replication*sigma^2group (please check the formula. It can be slightly > different when the model complexity increases). > > > Once, you get sigma^2 group, I guess you know how to calculate Vg and Vp. > > > Once, you have all the values, except sigma^2 group, you can subtract and > divide it by replication to get sigma^2 group. In SAS, proc glm also shows > the output with formula. > > A.K. >
Beware, though, that this works for balanced designs only (identical group sizes). For unequal replication, you need to go the lme/lmer route. -pd > > > > ----- Original Message ----- > From: Ista Zahn <istaz...@gmail.com> > To: tedtoal <twt...@ucdavis.edu> > Cc: r-help@r-project.org > Sent: Wednesday, July 25, 2012 6:21 AM > Subject: Re: [R] Between-group variance from ANOVA > > There is nothing about R in your question, hence it is not appropriate > for this list. Please consult with a local statistician, or post on a > stats help list such as http://stats.stackexchange.com/ > > On Tue, Jul 24, 2012 at 8:55 PM, tedtoal <twt...@ucdavis.edu> wrote: >> I'm trying also to understand how to get the between-group variance out of a >> one-way ANOVA, but I'm beginning to think that in a sense, the variance does >> not exist. Emma said: >> >> *The model is response(i,j)= group(i)+ error(i,j)* >> >> Yes, if by group(i) you mean intercept + coefficient[i]. >> >> *we assume that group~N(0,P^2) and error~N(0,sigma^2) * >> >> Only the error is assumed to be a random variable. Group is a fixed effect, >> not a random variable, and therefore it has no variance associated with it. >> The model does not predict a variance for it. One could compute the >> variance of the coefficients and call this a group variance, but it seems to >> me that isn't the right way to think about it. >> >> I'm trying to calculate a heritability value for a trait in an organism, >> defined as Vg/Vp, where Vg = variance due to genotype and Vp = total >> variance. The model is p~g, or p[i,j] = intercept + g_coefficient[i] + >> error[i,j]. But to get Vg, I think it is actually necessary to use a >> different model, where g is modelled as a random variable (a random effect), >> so the model can estimate a variance associated with it. >> >> If anyone can add something to this, please do. >> ted >> >> >> >> >> -- >> View this message in context: >> http://r.789695.n4.nabble.com/Between-group-variance-from-ANOVA-tp901535p4637686.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. > > ______________________________________________ > 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. -- Peter Dalgaard, Professor, Center for Statistics, Copenhagen Business School Solbjerg Plads 3, 2000 Frederiksberg, Denmark Phone: (+45)38153501 Email: pd....@cbs.dk Priv: pda...@gmail.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.
