[R] tweaking forest plot (metafor package)

Michael Dewey
Wed, 18 Jul 2012 17:15:37 -0000

At 00:10 18/07/2012, eesteves at ualg.pt wrote:
>Dear All,
>
>I'm having trouble tweaking a forest plot made using the R
>meta-analysis package metafor. I did the analysis based upon the
>correlation coeff from studies and plotted the corresponding forest
>plot easily
>
>>q2<-rma(yi,vi,mods=cbind(grupo),data=qim)
>>q2
>>forest (q2,transf=transf.ztor,digits=3, ... ,alim=c(0,1),refline=.5)
>>text(-1.55,42,"Esp?cie [ref?]",pos=4,font=2)

Not sure why you use cbind(grupo) but it will not change much.


>I'd like to subdivide the "table" by the moderator
'grupo' - i.e.
>create the necessary spacings in the list of studies to accommodate
>the moderator statistics (cf.
>http://rgm2.lab.nig.ac.jp/RGM2/func.php?rd_id=metafor:addpoly.default).
>
>My main issue is that I cannot really understand how the function
>(forest()) really uses space; specifically, how to use the parameters
>'xlim', 'ylim' and 'rows' in the function? how can I
change the scale
>from 0-1 to 0.5-1?

An example of what went wrong would help but I
think you will find that the rows argument tells
forest where to put the results of the individual
trials so if you give it non-consecutive integers
you will get gaps in the plot which you can fill
with addpoly. So if rows does not contain 4 you
can use addpoly to put something in row 4. As far
as xlim and ylim are concerned my advice would be
to try a whole range of values and see what
happens as this is one of those cases where it is
easier to experiment than to explain. If all else
fails either (a) look at the code (b) wait for
Wolfgang to ell you and me what really happens.

>Hopefully I've made myself (relatively) clear but... Thanks.
>
>Eduardo Esteves
>
>

Michael Dewey
info at aghmed.fsnet.co.uk