[R-sig-ME] (no subject)

[Angelo Franchini]

Hello,

I am trying to use the lme function part of the nlme package to perform a
random-effects meta-analysis at arm level, but I am not sure what is the
proper use that I should make of the weights option for this situation.
(By arm level I mean a meta-analysis that considers separately both
treatment arm and control arm outcomes, and not just the contrast between
them.)

The command that I am using is:
  out <- lme(o~s+t-1, random=~t-1 | s, weights=(~ se.o^2))

with
s as study/trial identifier
t as 0/1 for control/treatment arm
o as observed outcome in control or treatment arm
se.o as standard error of that outcome measure


I have looked through the R archives and forum and generally on the
Internet for clear indications on what to do, but have not found any.
Could anyone please help with that?

Many thanks.

Angelo