[R-meta] Q-Statistic for Between-Subgroup Heterogeneity

[Viechtbauer, Wolfgang (SP)]

Dear Ty,

Please always CC the mailing list.

And please re-read the posts under the link I posted (i.e., the entire thread). In particular, this one is most relevant:

https://stat.ethz.ch/pipermail/r-sig-meta-analysis/2017-December/000431.html

It shows how to fit a model with different tau^2 values per subgroup using metafor. See also:

http://www.metafor-project.org/doku.php/tips:comp_two_independent_estimates

Best,
Wolfgang

-----Original Message-----
From: Ty Beal [mailto:tbeal using gainhealth.org] 
Sent: Tuesday, 24 July, 2018 17:18
To: Viechtbauer, Wolfgang (SP)
Subject: RE: [R-meta] Q-Statistic for Between-Subgroup Heterogeneity

Dear Wolfgang,

If you do end up updating metafor to allow different between-subgroup heterogeneity, please let me know (if you remember). I may want to re-run the analysis to see how big of a difference it makes in uncertainty estimates.

Best,
Ty

-----Original Message-----
From: R-sig-meta-analysis <r-sig-meta-analysis-bounces using r-project.org> On Behalf Of Viechtbauer, Wolfgang (SP)
Sent: Monday, July 16, 2018 8:22 AM
To: r-sig-meta-analysis using r-project.org
Subject: Re: [R-meta] Q-Statistic for Between-Subgroup Heterogeneity

Good point. This was discussed before (for metagen(), but it's the same issue):

https://stat.ethz.ch/pipermail/r-sig-meta-analysis/2017-December/000430.html

Best,
Wolfgang

-----Original Message-----
From: R-sig-meta-analysis [mailto:r-sig-meta-analysis-bounces using r-project.org] On Behalf Of Guido Schwarzer
Sent: Monday, 16 July, 2018 13:13
To: r-sig-meta-analysis using r-project.org
Subject: Re: [R-meta] Q-Statistic for Between-Subgroup Heterogeneity

Am 13.07.18 um 18:31 schrieb Viechtbauer, Wolfgang (SP):

> [...]
> In the output, you will find:
>
> Test of Moderators (coefficients 2:3):
> QM(df = 2) = 1.7675, p-val = 0.4132
>
> This is the test for between-subgroup heterogeneity.

... assuming a common between-study variance tau2 across subgroups. The default in metaprop() of meta is to allow different between-study variances (analogous to RevMan 5, the software for Cochrane Reviews).
However, this can be changed using argument 'tau.common = TRUE' in metaprop().

As stated by Ty, metaprop() does not allow to specify the weights at the moment. I put this on my TODO list.

Best wishes,
Guido