dummy encoding in metafor

Mon, Jan 28, 2013 1:38 AM

Dear Alma,

either there is a whole lot of miscommunicaton here, or you (and your supervisor) are way in over your head.

You say that you are working with Cohen's d values. And you mentioned CMA. So, let me ask you some questions:

1) Has CMA computed those d values for you?
2) If yes, what information did you supply to CMA for the computation of those d values? (means, standard deviations, and the sample sizes of the two groups?)
3) Did CMA then provide you with a column of values that are the corresponding sampling variances or standard errors? (those values should NOT all be equal to 1!)

Best,
Wolfgang

________________________________
 From: Michael Dewey <info at aghmed.fsnet.co.uk>

t.co.uk>; "r-help at r-project.org" <r-help at r-project.org>
Sent: Thursday, January 24, 2013 6:57 PM
Subject: Re: [R] dummy encoding in metafor

At 22:06 23/01/2013, Alma Wilflinger wrote:

Hi Michael,

The supervisor for my Master's Thesis told me that my means are the
effect size and cause of this I have to take figure 1 for all standard
deviations. So I hope that was the right information.

Alma
There is a fairly comprehensive list of all the things which might be an
effect size on
http://en.wikipedia.org/wiki/Effect_size
Is what you call Mean one of them?

From: Michael Dewey <info at aghmed.fsnet.co.uk>

wolfgang.viechtbauer at maastrichtuniversity.nl>; Michael Dewey
<info at aghmed.fsnet.co.uk>; "r-help at r-project.org" <r-help at r-project.org>
Sent: Wednesday, January 23, 2013 10:22 AM
Subject: Re: [R] dummy encoding in metafor

At 08:30 23/01/2013, Alma Wilflinger wrote:
Dear Wolfgang and Michael,

[[elided Yahoo spam]]

Concerning the Variance: I took the variance I used for CMA (which
is always 1), so I think it should be the right one.

It seems unlikely to me that the variance from each study would be the
same although I suppose it could be possible. Are you sure you are
supplying the right values to CMA?

Thank you for noticing and mentioning though :)

I really appreciate how helpful you both are.

best,
Alma

dummy encoding in metafor

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