[R-meta] Meta-analysis - missing study-specific variance

Mon, Aug 21, 2023 12:40 PM

Hello Wolfgang,

Thank you very much for this guidance. Unfortunately I do not have the entire correlation matrices, and I only have the p-values for a small portion of included studies. So it looks like Option 2 is the most viable choice. 

Could you please direct me to which R package I would use (and/or any resources to consult) in order to understand and perform this? I am new to using R and meta-analysis, so any guidance you could provide would be incredibly helpful. 

Many thanks,
Angela

On Aug 21, 2023, at 3:53 AM, Viechtbauer, Wolfgang (NP) <wolfgang.viechtbauer at maastrichtuniversity.nl> wrote:

Attention : courriel externe | external email

Dear Angela,

You would need the entire correlation matrix of all variables involved in a regression model to compute the sampling variance of a standardized regression coefficient of such a model. I assume that this is not available to you.

I see a few alternative options:

1) Do you have the p-values corresponding to these regression coefficients? If so, you could use this to compute the partial correlation coefficients and conduct the meta-analysis using those. See:

https://wviechtb.github.io/metafor/reference/escalc.html#partial-and-semi-partial-correlations

2) You could fit a model that assumes that the sampling variances of the standardized regression coefficients are inversely proportional to the sample sizes and then use robust inference methods. Making this work isn't entirely straightforward, so I wouldn't suggest to consider this approach unless 1) is not an option.

Best,
Wolfgang

-----Original Message-----
From: R-sig-meta-analysis [mailto:r-sig-meta-analysis-bounces at r-project.org] On
Behalf Of Angela Leanne Wilson via R-sig-meta-analysis
Sent: Monday, 21 August, 2023 4:11
To: r-sig-meta-analysis at r-project.org
Cc: Angela Leanne Wilson
Subject: [R-meta] Meta-analysis - missing study-specific variance

Hello all,

I am conducting a meta-analysis to summarize effect sizes from different studies
that ran mediation analysis.

I have extracted the standardized regression coefficients (i.e., the indirect
effects from each mediation study) as the effect size. I also have the sample
size for each study, however I found that only a few studies reported any
error/variance estimate (probably because the authors have reported a
standardized regression coefficient and thus they did not report any
error/variance of the corresponding regression coefficient). In this case, it
means that many studies in my meta-analysis lack study-specific variance
information.

My understanding is that the study-specific variance is needed to calculate the
weight for each study when calculating the average effect size across studies.
May I ask if you can suggest what I need to do to estimate the study-specific
variance?

(Apologies I do not have any code as I cannot begin the analysis without first
resolving this issue)

Many thanks,
Angela

Angela Wilson (she, her/elle)
Doctoral Candidate, Clinical Psychology
University of Ottawa
Healthy Active Living and Obesity (HALO) Research Group
Children?s Hospital of Eastern Ontario (CHEO), Research Institute
Email: awils046 at uottawa.ca

[R-meta] Meta-analysis - missing study-specific variance

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