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

Michael Dewey lists at dewey.myzen.co.uk
Sat Oct 21 14:21:42 CEST 2017

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.
> 	[[alternative HTML version deleted]]
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