Hi Dr. Viechtbauer, Thank you very much. Putting in sei=se in forest() fixed the problem. Thanks for your help.
On 8 December 2015 at 08:37, Viechtbauer Wolfgang (STAT) < wolfgang.viechtba...@maastrichtuniversity.nl> wrote: > The first and second argument of forest() (or more precisely, > forest.default()) are for the estimates and the corresponding sampling > variances, respectively. So, if you do forest(rr, se, ...), then the > function will interpret the standard errors as if they are variances. So, > you should do forest(rr, sei=se, ...). > > And just in case: In all likelihood, those SEs are for the > *log-transformed* risk ratios, so you should also pass log-transformed risk > ratios to the function (and then use 'atransf=exp' so results are shown > with back-transformed x-axis labels and annotations). > > Best, > Wolfgang > > -- > Wolfgang Viechtbauer, Ph.D., Statistician | Department of Psychiatry and > Neuropsychology | Maastricht University | P.O. Box 616 (VIJV1) | 6200 MD > Maastricht, The Netherlands | +31 (43) 388-4170 | http://www.wvbauer.com > > > -----Original Message----- > > From: John Peterson [mailto:john.peterson....@gmail.com] > > Sent: Tuesday, December 08, 2015 14:25 > > To: Viechtbauer Wolfgang (STAT) > > Cc: R-help@r-project.org > > Subject: Re: [R] metafor package > > > > Hi Dr. Viechtbauer, > > > > The code provided in the metafor projects website for subgroup includes > > fitting a random effects model on the entire dataset and fitting a random > > effects model within subgroups. When I exactly follow this code, my > > estimates and confidence intervals for estimate within each subgroup > > matches with what I get in STATA so it seems to be the correct estimate > > (and CI). However, I don't want to present an overall effect and I want > > to present only the effect within each subgroup. In my second attempt, I > > did not run a random effects model within the entire dataset and only ran > > the models within each subgroup. I generated a variable corresponding to > > the estimate(risk ratio) and standard error which I plugged in the > > forest() function (i.e. forest(rr, se, .....). When I run this code, the > > estimate I get for each subgroup is slightly different than the estimate > > I get for each subgroup in comparison to when I also included the random > > effects model for the overall effect. (i.e. my first attempt). Is this > > the right approach? I was not clear when you said passing the estimates > > and sampling variances to the forest() function. I created a variable > > corresponding to the estimate and standard error and plugged those in the > > forest() function. I am not sure if this is the right approach. Thanks, > > > > John > > > > On 8 December 2015 at 03:47, Viechtbauer Wolfgang (STAT) > > <wolfgang.viechtba...@maastrichtuniversity.nl> wrote: > > Hi John, > > > > Please keep r-help copied on the reply. > > > > What's the 'previous model'? How do you get estimates within subgroups > > that 'includes the overall effect'? I really cannot follow you here. > > > > Best, > > Wolfgang > > > > -- > > Wolfgang Viechtbauer, Ph.D., Statistician | Department of Psychiatry and > > Neuropsychology | Maastricht University | P.O. Box 616 (VIJV1) | 6200 MD > > Maastricht, The Netherlands | +31 (43) 388-4170 | http://www.wvbauer.com > > > > > -----Original Message----- > > > From: John Peterson [mailto:john.peterson....@gmail.com] > > > Sent: Monday, December 07, 2015 22:14 > > > To: Viechtbauer Wolfgang (STAT) > > > Subject: Re: [R] metafor package > > > > > > Hi Dr. Viechtbauer, > > > Thank you very much for your reply. I tried your advice and was able to > > > make a forest plot with only the estimates for each subgroup.For the > > > estiamte for each subgroup, similar to the previous model, I random > > > effects model within each subgroup. However, I now find the result for > > > the estiamte within subgroup to be different thant the result for the > > > previous model. I have tried analyzing this in STATA and I get the same > > > result as the model which includes the overall effect. Any advice on > > what > > > may be wrong here? Thanks greatly, > > > John > > > > > > On 7 December 2015 at 04:02, Viechtbauer Wolfgang (STAT) > > > <wolfgang.viechtba...@maastrichtuniversity.nl> wrote: > > > The code you posted is totally mangled up, but it's just what can be > > > found here: > > > > > > http://www.metafor- > > project.org/doku.php/plots:forest_plot_with_subgroups > > > > > > If you don't want an overall estimate, just pass the estimates and > > > corresponding sampling variances to the forest() function (and not the > > > model object). Use the 'rows' argument to specify where the estimates > > > will be placed and adjust 'ylim' so give you enough space to leave gaps > > > for headings and the subgroup estimates. Then fit models within the > > > subgroups (the 'subset' argument is useful here) and use addpoly() to > > add > > > the subgroup estimates in the appropriate rows. With text(), you can > > add > > > headings as needed. > > > > > > If you use weights() on each subgroup model object, you can get the > > > subgroup weights (that add up to 100% within each subgroup). It's > > > probably easiest to just add those values with text() in an appropriate > > > place to the plot. > > > > > > Best, > > > Wolfgang > > > > > > -- > > > Wolfgang Viechtbauer, Ph.D., Statistician | Department of Psychiatry > > and > > > Neuropsychology | Maastricht University | P.O. Box 616 (VIJV1) | 6200 > > MD > > > Maastricht, The Netherlands | +31 (43) 388-4170 | > > http://www.wvbauer.com > > > > > > > -----Original Message----- > > > > From: R-help [mailto:r-help-boun...@r-project.org] On Behalf Of John > > > > Peterson > > > > Sent: Monday, December 07, 2015 01:39 > > > > To: r-help@r-project.org > > > > Subject: [R] metafor package > > > > > > > > Hi Everyone, > > > > > > > > I am conducting a meta-analysis using the metafor package. I am > > > > interested > > > > in obtaining an estimate by subgroup only without showing an overall > > > > effect. This is directly from the metafor website. How would i modify > > > > this > > > > code to only show subgroup effects? Further, I want to show weights > > by > > > > subgroup. The option showweights=TRUE does not display weights by > > > > subgroup > > > > but by the weight of each study in comparison to all studies (and not > > > the > > > > subgroup). You help would be appreciated. > > > > [snip garbled code] > [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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.
