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#### Options  Subscribe or Unsubscribe   Log In   Get Password Subject: Re: Meta-analysis using weighted mean approach

From:  Date: Wed, 30 Aug 2006 08:23:59 +0200

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 ```Dear all, I received some valuable replies and I am now able to present a solution to my problem. A special thank goes to Georgia Salanti. She kindly explained to me that "in Bayesian framework however , where talking about SE does not make sense, the `weight´ (the idea that small studies contribute less than big studies) is conveyed in a distributional way". I also re-discoverd an article by Sharon-Lise T. Normand , which clearly demonstrates what to do (p 344-345). Below is my adaption (for OpenBUGS) of her BUGS-code: # Bayesian random effects model # d=risk difference, var.d=variance model{ for(i in 1:K){ sinv[i] <- 1/(var.d[i]); d[i] ~ dnorm(theta[i],sinv[i]); theta[i] ~ dnorm(mu,sigma) } mu ~ dnorm(0.0,0.000001); sigma ~ dgamma(0.001,0.001); tau <- 1/sigma; } # data list(d = c(0.028, 0, 0.02, 0.018, 0.035, 0.044),var.d = c(0.002, 0.004, 0.001, 0.001, 0.001, 0.001),K=6) # inits list(mu=0,sigma=1,theta=c(0,0,0,0,0,0)) Kind regards, Bernd Weiss  Normand, Sharon-Lise T., 1999: Tutorial in Biostatistics. Meta- Analysis: Formulating, Evaluating, Combining, and Reporting, Statistics in Medicine 18: 321--359.  Maybe, someone is interested in comparing the Bayesian findings to a conventional random effects model. Here's some R code... library(meta) n.t <- c(39,44,107,103,110,154) n.c <- c(43,44,110,100,106,146) e.t <- c(2,4,6,7,7,11) e.c <- c(1,4,4,5,3,4) p.t <- e.t/(n.t) p.c <- e.c/n.c # risk difference rd <- p.t-p.c sd.rd <- sqrt((p.t*(1-p.t)/n.t)+(p.c*(1-p.c)/n.c)) var.rd <- sd.rd^2 metabin(e.t,n.t,e.c,n.c,sm="RD",method="Inverse") # odds ratio or <- (p.t/(1-p.t))/(p.c/(1-p.c)) log.or <- log(or) sd.log.or <- sqrt(1/e.t+1/(n.t-e.t)+1/e.c+1/(1-n.c)) var.log.or <- sd.log.or^2 metabin(e.t,n.t,e.c,n.c,sm="OR",method="Inverse") ------------------------------------------------------------------- This list is for discussion of modelling issues and the BUGS software. For help with crashes and error messages, first mail [log in to unmask] To mail the BUGS list, mail to [log in to unmask] Before mailing, please check the archive at www.jiscmail.ac.uk/lists/bugs.html Please do not mail attachments to the list. To leave the BUGS list, send LEAVE BUGS to [log in to unmask] If this fails, mail [log in to unmask], NOT the whole list ```