[R-meta] Calculating standard errors from confidence interval and weights assigned

[Win Thu]

Dear Michal - thank you for the feedback.
Dear Wolgang - thank you for the correction about syntax. I used the
correct one rma(yi, sei=sei, data) in the analysis and was unsure about the
weights assigned to each study.

Thank you,
Win








On Thu, Jul 13, 2023 at 2:35 AM Viechtbauer, Wolfgang (NP) via
R-sig-meta-analysis <r-sig-meta-analysis using r-project.org> wrote:

> This aside, the syntax rma(yi, sei, data) is wrong, since the second
> argument to rma() is 'vi', which is for the *sampling variances* (i.e., the
> squared standard errors). So, either do rma(yi, sei^2, data) or use the
> appropriate argument for passing the standard errors, that is, rma(yi,
> sei=sei, data).
>
> In recent versions of metafor, rma() actually tries to check for this
> (based on the variable name specified for the 'vi' argument), so syntax
> like rma(yi, sei) should yield a warning about this.
>
> Best,
> Wolfgang
>
> >-----Original Message-----
> >From: R-sig-meta-analysis [mailto:
> r-sig-meta-analysis-bounces using r-project.org] On
> >Behalf Of Michael Dewey via R-sig-meta-analysis
> >Sent: Wednesday, 12 July, 2023 16:09
> >To: R Special Interest Group for Meta-Analysis
> >Cc: Michael Dewey
> >Subject: Re: [R-meta] Calculating standard errors from confidence
> interval and
> >weights assigned
> >
> >Dear Win
> >
> >If you fit a random-effects model then the weights become more nearly
> >equal tending to equality as tau^2 increases. I suspect that may be the
> >issue here.
> >
> >Michael
> >
> >On 12/07/2023 05:36, Win Thu via R-sig-meta-analysis wrote:
> >> Hello,
> >>
> >> I would like to seek your opinions on calculating standard error (sei)
> >> from confidence intervals, and weights assigned to each study in a
> >> random effects model.
> >> To include in rma function*rma(yi, sei, data)*, I used the following
> >> formula to calculate sei
> >>
> >> *sei <- [log(CI upper limit) - log(CI lower limit)] / 3.92 *
> >> For yi, it will be log(relative risk).
> >>
> >> Then, I have the following weights for each study, which I am not very
> >> confident as the studies with larger sample sizes (cohort studies) were
> >> given reduced weights compared to smaller studies (case-control).
> >> I need to combine both studies as there are limited studies on the
> topic.
> >>
> >> I am grateful for your feedback.
> >>
> >> Untitled.png
> >> Thank you,
> >> Win
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