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

[Michael Dewey]

Dear Cesar

I think you have to tell the journal that this is not possible and 
provide the data-set with NA for the unavailable fields.

Michael

On 26/02/2018 15:04, Cesar Terrer Moreno wrote:
> I currently have a dataset of 300 observations structures as MeanControl, MeanTreated, SEControl, SETreated, Ncontrol, Ntreated, and I calculate ES and VAR through metafor:escalc.
> 
>   
> 
> Now, I found a few observations that provide only ES and VAR, which I would like to add to the original dataset.
> 
>   
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> Obviously I could include these new observations ad-hoc to the post-escalc dataset, but journal suggests providing the raw data  with the above fields as MeanControl, MeanTreated, etc so all observations are in the same format. For this reason, I want to back-transform from ES-VAR to MEAN-SE.
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>   
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> C
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> De: James Pustejovsky [mailto:jepusto at gmail.com]
> Enviado el: 26 February 2018 15:56
> 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
> 
>   
> 
> No, that's not possible. But why do you need to do this? Couldn't you just use the ES and VAR directly?
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>   
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> On Mon, Feb 26, 2018 at 8:53 AM, Cesar Terrer Moreno <cesar.terrer at me.com <mailto:cesar.terrer at me.com> > wrote:
> 
> Dear James,
> 
>   
> 
> I believe you are right, 1.38 is the effect size, and 0.07 the error of the effect size.
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>   
> 
> 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
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>   
> 
> MeanControl = 1
> 
> MeanTreated = 1.38
> 
> SEControl = ?
> 
> SETreated = ?
> 
>   
> 
> De: James Pustejovsky [mailto:jepusto at gmail.com <mailto:jepusto at gmail.com> ]
> Enviado el: 26 February 2018 15:45
> Para: Cesar Terrer Moreno <cesar.terrer at me.com <mailto:cesar.terrer at me.com> >
> CC: r-sig-meta-analysis at r-project.org <mailto: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.
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> James
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> 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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-- 
Michael
http://www.dewey.myzen.co.uk/home.html