[R-meta] rma with already available pre-post changes; yi=yi

P. Roberto Bakker robertobakker at gmail.com
Sun Oct 22 07:54:20 CEST 2017


Dear Michael,

Thank you for your explanations.

Yes I use vi=se^2; my apologies for not being clear.
Now we talk about this, I learned in statistics that vi=sd^2 - but I read
in every literature about meta-analysis that vi=se^2. How can I see this?

About posting in plain text; you mean text like in notepad? So, I copy/past
text from notepad into mail?

Bw,
Roberto

2017-10-21 14:21 GMT+02:00 Michael Dewey <lists at dewey.myzen.co.uk>:

> Dear Roberto
>
> On 21/10/2017 05:28, P. Roberto Bakker wrote:
>
>> Hi,
>>
>> I want to meta-analyze pre-post change measures between treatment vs
>> placebo.
>> I got already delivered the Hedges g between the two arms and  their SE
>> Hedges g.
>> So I used res <- rma(measure="SMCC", yi=yi, vi=vi, data=datsub, digits=2,
>> method = "REML")
>>
>>
> That is fine if your vi is indeed the variance but you said you have the
> standard error in which case you would need vi = se ^ 2 or se = se
>
> My questions:
>> Do I need to use SMCC  in rma()? I suppose 'measure=' is necessary in
>> escalc()
>>
>
> Yes, that is correct since you have got the general case here where you
> specify yi and vi (or sei) and rma neither knows not cares where on earth
> they came from.
>
> I see no difference in SMCC/SMCR etc. So I suppose it is not necessary. I
>> only use it for the forest() scale title.
>>
>> Do I use yi=yi or just yi? As ask this because I was adviced in a former
>> mail to use sei=sei instead of sei, the same voor vi.
>>
>
> It is always safest to use the explicit parameter names in case you forget
> their order.
>
>
>> Bw
>> Roberto
>>
>
> It would be good to post in plain text in case future posts get mangled,
> being in HTML. This one got through OK.
>
>>
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>>
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>>
>>
> --
> Michael
> http://www.dewey.myzen.co.uk/home.html
>

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