[R-meta] converting escalc ROM outputs to the log-2 scale

Divya Ravichandar d|vy@ @end|ng |rom @econdgenome@com
Sat Dec 12 01:09:56 CET 2020


Hi Dr. Wolfgang

Thank you for getting back to me. Could you help me understand more on why
we square the log(2) in the vi calculation?



On Fri, Dec 11, 2020 at 6:37 PM Viechtbauer, Wolfgang (SP) <
wolfgang.viechtbauer using maastrichtuniversity.nl> wrote:

> Dear Divya,
>
> If y_i ~ N(theta_i, v_i), then for any constant c, c*y_i ~ N(c*theta_i,
> c^2 * v_i).
>
> So, it would be yi_new = yi/log(2) and vi_new = vi/log(2)^2.
>
> Best,
> Wolfgang
>
> >-----Original Message-----
> >From: R-sig-meta-analysis [mailto:
> r-sig-meta-analysis-bounces using r-project.org]
> >On Behalf Of Divya Ravichandar
> >Sent: Friday, 11 December, 2020 23:36
> >To: r-sig-meta-analysis using r-project.org
> >Subject: [R-meta] converting escalc ROM outputs to the log-2 scale
> >
> >Hi all
> >
> >I have a question around changing the scale of *yi *and *vi *exported
> >from *escalc()
> >*function when using *measure=ROM.* Based on the documentation, this
> >function exports *yi *in natural log (ln) scale. --> yi =
> >ln(grp1-mean/grp2-mean) and then the associated vi.
> >
> >I am interested in obtaining the *log-2 fold change. *Is there a way to
> >convert yi & vi from *escalc(measure = ROM,...) *to this scale. Would it
> be
> >reasonable to simply transform the values by converting from log-e ->
> log-2
> >scale by
> >yi_new = yi/log(2) and vi_new = vi/log(2)
> >
> >Thank you
> >
> >--
> >*Divya Ravichandar*
> >Scientist
> >Second Genome
>


-- 
*Divya Ravichandar*
Scientist
Second Genome

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