# [R-meta] Calculate individual SDs from ES's SDs

Cesar Terrer Moreno cesar.terrer at me.com
Mon Feb 26 15:53:05 CET 2018

```Dear James,

I believe you are right, 1.38 is the effect size, and 0.07 the error of the effect size.

My question is whether I can compute the standard error of the control and treated groups having the effect size’s SE/SD.

ES = 1.38

VAR = 0.07^2

MeanControl = 1

MeanTreated = 1.38

SEControl = ?

SETreated = ?

De: James Pustejovsky [mailto:jepusto at gmail.com]
Enviado el: 26 February 2018 15:45
Para: Cesar Terrer Moreno <cesar.terrer at me.com>
CC: r-sig-meta-analysis at r-project.org
Asunto: Re: [R-meta] Calculate individual SDs from ES's SDs

I would hazard a guess that the +/- 0.07, which is described as "SD", might actually be the standard error of the effect size estimate. So in the example, ES = 1.38 and sampling variance = 0.07^2 = 0.049. Perhaps you can verify this speculation using other information in the source document.

James

On Wed, Feb 21, 2018 at 6:41 AM, Cesar Terrer Moreno <cesar.terrer at me.com <mailto:cesar.terrer at me.com> > wrote:

Dear all,

I have a series of effects sizes, expressed as e.g.:

1.38 ± 0.07 (MEANexp/MEANcontrol, SD, n=3)

I have to express these experiments as MEANexp, SDexp, MEANcontrol, SDcontrol in order to put all data in a correct formar that can be read by escalc in metafor.

I guess I can assume MEANexp = 1.38 and MEANcontrol = 1, but how can I compute SDs so that escalc computes the effect size’s variance properly?

Thanks
César
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