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

-----Original Message-----
From: Divya Ravichandar [mailto:divya at secondgenome.com]
Sent: Saturday, 12 December, 2020 1:10
To: Viechtbauer, Wolfgang (SP)
Cc: r-sig-meta-analysis at r-project.org
Subject: Re: [R-meta] converting escalc ROM outputs to the log-2 scale

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 at 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 at r-

project.org]

On Behalf Of Divya Ravichandar
Sent: Friday, 11 December, 2020 23:36
To: r-sig-meta-analysis at 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