[R] Metafor: Strange Trim and Fill Outcome?

[Michael Dewey]

At 09:34 26/05/2014, Verena Weinbir wrote:
>Hey guys,
>
>I have tested the metafor trim and fill function (y:SD, x:SMD)on my data
>set and yielded the following result:
>
>1. missing studies on the right: 34

That seems a lot of missing studies unless you have a very large set 
of primary studies.


>2. open circles on the rights side appear to be the number of additional
>effects
>
>3. adjusted d would be higher than observed d.

Implying that the mechanism is suppressing studies which found a 
large effect. This might happen if the dominant view is that there is 
no effect and so when people find one they worry about their results.


>Since normally, as I understand, those parameters are the other way round
>(black dots indicating missing studies on the left, which would reduce the
>effect size), I wonder:
>
>Is there a mistake I have done? Or, if this is an actual outcome how can I
>interpret this?  That its not a publication bias that influences my data
>set, but a lack of precision (studies missing that are precise -small SD-
>and have big SMD)?

Sorry but that bit is not very clear to me.

>Many thanks in advance!
>
>Verena
>
>         [[alternative HTML version deleted]]

Michael Dewey
info at aghmed.fsnet.co.uk
http://www.aghmed.fsnet.co.uk/home.html