Dear Mario, If you could tell me how to define and interpret I^2 and H^2 for models with moderators, I may consider implementing these measures for such models. However, I am not aware of any work that has extended these measures to meta-regression models.
Best, -- Wolfgang Viechtbauer Department of Psychiatry and Neuropsychology School for Mental Health and Neuroscience Maastricht University, P.O. Box 616 6200 MD Maastricht, The Netherlands Tel: +31 (43) 368-5248 Fax: +31 (43) 368-8689 Web: http://www.wvbauer.com > -----Original Message----- > From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] > On Behalf Of petre...@unina.it > Sent: Sunday, February 20, 2011 13:59 > To: r-help@r-project.org > Subject: [R] Help Metafor > > Dear Sir, I'm using the "Metafor" package; > > however, introducing moderators, I'm unable to obtain both I^2 (% > of total variability due to heterogeneity) and H^2 (total variability > / within-study variance). It is possible to obtain I^2 and H^2 also > with moderators? > > As example > > _Dataset <- sqlQuery(channel = 1, select * from [Foglio1$]) > names(Dataset) <- make.names(names(Dataset)) > alloc.a <- ifelse(dat$alloc == "a", 1, 0) > alloc.b <- ifelse(dat$alloc == "b", 1, 0) > alloc.c <- ifelse(dat$alloc == "c", 1, 0) > > res<-rma.uni(yi, vi, mods=cbind(alloc.a, alloc.b, Year), > measure="GEN", intercept=TRUE, data=dat, slab=Author, subset, add=1/2, > to="only0", vtype="LS", method="REML", weighted=TRUE, knha=FALSE, > btt=c(2,3)) > > > print (res) > > Mixed-Effects Model (k = 22; tau^2 estimator: REML) > tau^2 (estimate of residual amount of heterogeneity): 0.7810 (SE = 0.2924) > tau (sqrt of the estimate of residual heterogeneity): 0.8838 > > Test for Residual Heterogeneity: > QE(df = 18) = 223.3159, p-val < .0001 > > Test of Moderators (coefficient(s) 2,3): > QM(df = 2) = 0.8251, p-val = 0.6620 > > Model Results: > > estimate se zval pval ci.lb ci.ub > intrcpt -135.3524 54.4487 -2.4859 0.0129 -242.0700 -28.6349 * > alloc.a -0.3836 0.4529 -0.8469 0.3971 -1.2713 0.5042 > alloc.b -0.3656 0.5529 -0.6613 0.5084 -1.4493 0.7180 > Year 0.0673 0.0273 2.4677 0.0136 0.0139 0.1208 * > > Many thanks > > _________________________________________ > > Mario Petretta > Dipartimento di Medicina Clinica Scienze Cardiovascolari e Immunologiche > Facoltà di Medicina e Chirurgia > Università di Napoli Federico II > 081 - 7462233 ______________________________________________ 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.
