R help - Jun 2013 - Add prediction interval forest plot (package "meta")

Dear all,

I am struggling to add a prediction interval to a forest plot that was
created with forest.meta(), package "meta".

I checked the source of forest.meta() and realized that it is heavily
relying on grid. I am lacking any experience with grid graphics. So, I
am having difficulties to find out where the random effects estimate is
actually plotted in order to add prediction intervals.

Any help is much appreciated!

Bernd


R version 3.0.1 Patched (2013-05-28 r62825)
Platform: x86_64-w64-mingw32/x64 (64-bit)

locale:
[1] LC_COLLATE=German_Germany.1252  LC_CTYPE=German_Germany.1252
LC_MONETARY=German_Germany.1252
[4] LC_NUMERIC=C                    LC_TIME=German_Germany.1252

attached base packages:
[1] grid      stats     graphics  grDevices utils     datasets  methods
  base

other attached packages:
[1] meta_2.3-0

loaded via a namespace (and not attached):
[1] tools_3.0.1

At 19:34 06/06/2013, Bernd Weiss wrote:
>Dear all,
>
>I am struggling to add a prediction interval to a forest plot that was
>created with forest.meta(), package "meta".
>
>I checked the source of forest.meta() and realized that it is heavily
>relying on grid. I am lacking any experience with grid graphics. So, I
>am having difficulties to find out where the random effects estimate is
>actually plotted in order to add prediction intervals.
I appreciate this is not a direct answer to your question but the 
equivalent function in metafor (available from CRAN) does this and it 
might be easier to use that.

>Any help is much appreciated!
>
>Bernd
>
>
>R version 3.0.1 Patched (2013-05-28 r62825)
>Platform: x86_64-w64-mingw32/x64 (64-bit)
>
>locale:
>[1] LC_COLLATE=German_Germany.1252  LC_CTYPE=German_Germany.1252
>LC_MONETARY=German_Germany.1252
>[4] LC_NUMERIC=C                    LC_TIME=German_Germany.1252
>
>attached base packages:
>[1] grid      stats     graphics  grDevices utils     datasets  methods
>   base
>
>other attached packages:
>[1] meta_2.3-0
>
>loaded via a namespace (and not attached):
>[1] tools_3.0.1
Michael Dewey
info at aghmed.fsnet.co.uk
http://www.aghmed.fsnet.co.uk/home.html