[R-meta] sample size correlations for meta-analysis

[Lukasz Stasielowicz]

Dear Catia,

Similarly to Michael Dewey, I have the impression that researchers 
usually define an arbitrary cut-off value to exclude small samples.

If you want to use empirical data to justify excluding studies, then the 
following article could be helpful:

Schönbrodt, F. D., & Perugini, M. (2013). At what sample size do 
correlations stabilize? Journal of Research in Personality, 47(5), 
609–612. https://doi.org/10.1016/j.jrp.2013.05.009



Best,
Lukasz
-- 
Lukasz Stasielowicz
Osnabrück University
Institute for Psychology
Research methods, psychological assessment, and evaluation
Lise-Meitner-Straße 3
49076 Osnabrück (Germany)
Twitter: https://twitter.com/l_stasielowicz

On 16.07.2023 12:00, r-sig-meta-analysis-request using r-project.org wrote:
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>     1. Re: origin of "sandwich" (Sicong Liu)
>     2. sample size correlations for meta-analysis (Catia Oliveira)
>     3. Re: sample size correlations for meta-analysis (Michael Dewey)
> 
> ----------------------------------------------------------------------
> 
> Message: 1
> Date: Sat, 15 Jul 2023 11:07:31 +0000
> From: Sicong Liu <64zone using gmail.com>
> To: James Pustejovsky <jepusto using gmail.com>, R Special Interest Group
> 	for Meta-Analysis <r-sig-meta-analysis using r-project.org>
> Subject: Re: [R-meta] origin of "sandwich"
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> 
> Good morning James,
> 
> That is an unbeatable description and thanks a bunch!
> 
> I am going to have a big breakfast later 😊
> 
> Cheers,
> Sicong
> -------------
> 
> 
> From: James Pustejovsky <jepusto using gmail.com>
> Date: Friday, July 14, 2023 at 10:03 PM
> To: R Special Interest Group for Meta-Analysis <r-sig-meta-analysis using r-project.org>
> Cc: Sicong Liu <64zone using gmail.com>
> Subject: Re: [R-meta] origin of "sandwich"
> 
> Hi Sicong,
> 
> Your impression is correct. It's called a sandwich estimator because the formula looks like a sandwich. It has the same quantity, called the "bread," on both sides, with a quantity called the "meat" in the middle. See Kaureman & Carroll (2001) for a technical explainer:
> https://www.jstor.org/stable/3085907
> 
> We can torture this analogy further by noting that the meat matrix consist of a bunch of slices---one for each cluster---so it really is like slices of baloney or salami or something. Furthermore, if you consider the slices individually, they are poor quality estimators of what we're trying to quantify. But if you stack enough of them together, they work well enough (...to satisfy your grumbling stomach...).
> 
> My clubSandwich package gets its name from the fact that it implements sandwich-type formulas, but with extra "filling" in the middle of the sandwich---not just meat,  but also some sprouts, Swiss cheese, thousand island dressing, etc. The extra filling is there to improve the performance of the sandwich estimator when you only have a few independent slices of meat. I've explained this analogy in a few talks I've given, e.g.: https://www.jepusto.com/talk/oslorug-2022-clubsandwich/
> The reactions have varied from polite chuckles to outright eye rolling, depending on how hungry the audience is. Your mileage may vary.
> 
> James
> 
> On Fri, Jul 14, 2023, 3:15 PM Sicong Liu via R-sig-meta-analysis <r-sig-meta-analysis using r-project.org<mailto:r-sig-meta-analysis using r-project.org>> wrote:
> Dear All,
> 
> I have a burning question regarding the origin of the word “sandwich” that frequently appears in meta-analysis (e.g., “Egger sandwich test” and the R package “clubSandwich”). Could some meta tycoon(s) share knowledge/discussion on this?
> 
> My vague impression was that “sandwich” may relate to the looking of a linear algebra expression for computing uncertainties. However, I could no longer identify this source (a book I think) and feel much bothered by it. Thank you all in advance!
> 
> Best regards,
> Sicong (Zone)
> 
> ---------------------------------------------------------
> Sicong (Zone) Liu, Ph.D.
> Research Associate
> University of Pennsylvania
> 
> 3620 Walnut Street,
> Philadelphia, PA 19104-6220
> Email: zone using upenn.edu<mailto:zone using upenn.edu><mailto:zone using upenn.edu<mailto:zone using upenn.edu>>
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> ------------------------------
> 
> Message: 2
> Date: Sat, 15 Jul 2023 17:00:35 +0100
> From: Catia Oliveira <catia.oliveira using york.ac.uk>
> To: R meta <r-sig-meta-analysis using r-project.org>
> Subject: [R-meta] sample size correlations for meta-analysis
> Message-ID:
> 	<CACw+TfcnMk7BgdC+AqwJFTwZrFK2VuUmkK01x7koUk8Sj7L58w using mail.gmail.com>
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> 
> Dear all,
> 
> I hope this email finds you well.
> I was wondering if anyone has ever published or seen a published paper that
> reflects on the minimum sample size for correlations to be used in
> meta-analysis? We may need to look at the raw data to see if participants
> fit the inclusion criteria, leaving us with very small sample sizes, so we
> want to establish what would be too small to reject. I know we need to
> ensure that the sample size needs to be big enough to allow for estimating
> the correlation and its confidence interval, but is that enough?
> 
> Thank you!
> 
> Best wishes,
> 
> Catia
>