[R-meta] paired meta-analyzes with different n for loss of patients to follow-up

Gerta Ruecker ruecker @end|ng |rom |mb|@un|-|re|burg@de
Fri Apr 24 10:09:55 CEST 2020 

Dear Martin,


This is about missing data and I'm not an expert on this. As there is 
uncertainty, probably the smaller n (the post) should be used. However, 
and more importantly, there is also uncertainty about the estimates, if 
you cannot assume that your data are missing at random.


Best,

Gerta



Am 22.04.2020 um 20:41 schrieb Martin Lobo:
> hello, one new question !!!
>
> paired meta-analyzes with different n for loss of patients to follow-up
> what n use, the pre or the post.
>
>
> best regard
>
>
> Martin
>
>
> */
> /*
> */Lorenzo Martín Lobo /**/^MTSAC, FACC, FESC /*
> /*Especialista Jerarquizado en Cardiología*/
> /*/*Jefe de Dpto Enf. Cardiovasculares y Cardiometabolismo Hospital 
> Militar Campo de Mayo.*/
> */
> /*/*Jefe de Cardiología *//*Hospital Militar Campo de Mayo*/
> */
> /*Ex Jefe de Unidad Coronaria *//*Hospital Militar Campo de Mayo*/
> /
> /*Miembro Titular de la Sociedad Argentina de Cardiología*/
> /
> /
> /*Fellow American College of Cardiology*/
> /
> /
> /*Fellow European Society of Cardiology*/
> /
> /
> /*/*Ex Miembro del Area de Investigación de la SAC*/*/
> /
> /*Ex Director del Consejo de Aterosclerosis y Trombosis de la SAC*/
> /*Miembro Asesor /*del Consejo de Aterosclerosis y Trombosis de la SAC*/*/
> /*/
> /*/
> /*Ex Director del Consejo de Epidemiología y Prevención Cardiovascular 
> de la SAC*/
> /*/
> /*/
> /*/
> /*//*/
> /*/
> /*Miembro Asesor del Consejo de Epidemiología y Prevención 
> Cardiovascular de la SAC*/
> /*/
> /*/
> /*/
> /*/
> /*Experto en Lipidos de la Sociedad Argentina de Lipidos.*/
> /*Miembro de la Sociedad Argentina de Lipidos.*/
> /
> /*Instructor de ACLS de la American Heart Association*/
> /
>
>
> ------------------------------------------------------------------------
> *De:* Gerta Ruecker <ruecker using imbi.uni-freiburg.de>
> *Enviado:* miércoles, 22 de abril de 2020 11:16
> *Para:* Martin Lobo <mlobo4370 using hotmail.com>; 
> r-sig-meta-analysis using r-project.org <r-sig-meta-analysis using r-project.org>
> *Asunto:* Re: [R-meta] meta analysis with standard deviation or 
> standard errors
>
> For paired samples (changes, differences) I would preferably use MD.
>
>
> Gerta
>
>
> Am 22.04.2020 um 16:02 schrieb Martin Lobo:
>> THANK YOU GERTA !!!
>>
>> Ok
>>
>> For individual samples I use MD or SMD, depending on whether the 
>> measurements are on the same scale or not.
>>
>> for paired samples, should i use MC or SMCC?
>>
>> Regard
>>
>>
>>
>> */
>> /*
>> */Lorenzo Martín Lobo /**/^MTSAC, FACC, FESC /*
>> /*Especialista Jerarquizado en Cardiología*/
>> /*/*Jefe de Dpto Enf. Cardiovasculares y Cardiometabolismo Hospital 
>> Militar Campo de Mayo.*/
>> */
>> /*/*Jefe de Cardiología *//*Hospital Militar Campo de Mayo*/
>> */
>> /*Ex Jefe de Unidad Coronaria *//*Hospital Militar Campo de Mayo*/
>> /
>> /*Miembro Titular de la Sociedad Argentina de Cardiología*/
>> /
>> /
>> /*Fellow American College of Cardiology*/
>> /
>> /
>> /*Fellow European Society of Cardiology*/
>> /
>> /
>> /*/*Ex Miembro del Area de Investigación de la SAC*/*/
>> /
>> /*Ex Director del Consejo de Aterosclerosis y Trombosis de la SAC*/
>> /*Miembro Asesor /*del Consejo de Aterosclerosis y Trombosis de la 
>> SAC*/*/
>> /*/
>> /*/
>> /*Ex Director del Consejo de Epidemiología y Prevención 
>> Cardiovascular de la SAC*/
>> /*/
>> /*/
>> /*/
>> /*//*/
>> /*/
>> /*Miembro Asesor del Consejo de Epidemiología y Prevención 
>> Cardiovascular de la SAC*/
>> /*/
>> /*/
>> /*/
>> /*/
>> /*Experto en Lipidos de la Sociedad Argentina de Lipidos.*/
>> /*Miembro de la Sociedad Argentina de Lipidos.*/
>> /
>> /*Instructor de ACLS de la American Heart Association*/
>> /
>>
>>
>> ------------------------------------------------------------------------
>> *De:* Gerta Ruecker <ruecker using imbi.uni-freiburg.de> 
>> <mailto:ruecker using imbi.uni-freiburg.de>
>> *Enviado:* miércoles, 22 de abril de 2020 10:26
>> *Para:* Martin Lobo <mlobo4370 using hotmail.com> 
>> <mailto:mlobo4370 using hotmail.com>; r-sig-meta-analysis using r-project.org 
>> <mailto:r-sig-meta-analysis using r-project.org> 
>> <r-sig-meta-analysis using r-project.org> 
>> <mailto:r-sig-meta-analysis using r-project.org>
>> *Asunto:* Re: [R-meta] meta analysis with standard deviation or 
>> standard errors
>>
>> Dear Martin,
>>
>>
>> I am not sure whether I understand you correctly, but I see the 
>> following cases:
>>
>>  1. You have pre-post changes (differences) with sd (or se) of these
>>     changes -> you can use these for pooling
>>  2. You have pre values and post values and their intra-individual
>>     correlations (not frequently the case) -> you can use the
>>     correlations to calculate the sd/se for the differences (and then
>>     pool as in case 1)
>>  3. You have pre values and post values, but no correlations and no
>>     sd or se for the differences -> you might impute a correlation
>>     and proceed as in case 2
>>  4. You can also mix pre-post changes and post values, but only for
>>     mean differences, not for standardized mean differences, see
>>     Cochrane Handbook
>>     https://training.cochrane.org/handbook/current/chapter-10#section-10-5-2
>>     <https://eur05.safelinks.protection.outlook.com/?url=https%3A%2F%2Ftraining.cochrane.org%2Fhandbook%2Fcurrent%2Fchapter-10%23section-10-5-2&data=02%7C01%7C%7C50bd0edfa39a4d34702f08d7e6c7caeb%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637231618285603045&sdata=VYSIicza9TQ%2Fuj5zZEwtd19GAO1Qn0Z4RhOyTSzztig%3D&reserved=0>
>>
>> Best,
>>
>> Gerta
>>
>>
>>
>> Am 22.04.2020 um 14:30 schrieb Martin Lobo:
>>> Dear Gerta, thank tou very mucha for tour time.
>>>
>>>
>>> 1- the MC and SMCC are the methods I found for paired samples on 
>>> page 103 of the metafor manual, I understood that they were 
>>> equivalent to the MD and SMD of the individual samples.
>>> Manual Link: 
>>> https://cran.r-project.org/web/packages/metafor/metafor.pdf 
>>> <https://eur05.safelinks.protection.outlook.com/?url=https%3A%2F%2Fcran.r-project.org%2Fweb%2Fpackages%2Fmetafor%2Fmetafor.pdf&data=02%7C01%7C%7C50bd0edfa39a4d34702f08d7e6c7caeb%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637231618285613037&sdata=Us9VTOVTOQLicqIv1ZvHqzKXRHXCBsbmgzNEwF4XnOM%3D&reserved=0>
>>>
>>>
>>> If I had the pre post standard averages and deviations, only the 
>>> difference with your
>>> standard deviation, would I no longer need the ri? In that case what 
>>> method do I use
>>> or what code?
>>>
>>> thank you so much
>>> Martin
>>> */
>>> /*
>>> */Lorenzo Martín Lobo /**/^MTSAC, FACC, FESC /*
>>> /*Especialista Jerarquizado en Cardiología*/
>>> /*/*Jefe de Dpto Enf. Cardiovasculares y Cardiometabolismo Hospital 
>>> Militar Campo de Mayo.*/
>>> */
>>> /*/*Jefe de Cardiología *//*Hospital Militar Campo de Mayo*/
>>> */
>>> /*Ex Jefe de Unidad Coronaria *//*Hospital Militar Campo de Mayo*/
>>> /
>>> /*Miembro Titular de la Sociedad Argentina de Cardiología*/
>>> /
>>> /
>>> /*Fellow American College of Cardiology*/
>>> /
>>> /
>>> /*Fellow European Society of Cardiology*/
>>> /
>>> /
>>> /*/*Ex Miembro del Area de Investigación de la SAC*/*/
>>> /
>>> /*Ex Director del Consejo de Aterosclerosis y Trombosis de la SAC*/
>>> /*Miembro Asesor /*del Consejo de Aterosclerosis y Trombosis de la 
>>> SAC*/*/
>>> /*/
>>> /*/
>>> /*Ex Director del Consejo de Epidemiología y Prevención 
>>> Cardiovascular de la SAC*/
>>> /*/
>>> /*/
>>> /*/
>>> /*//*/
>>> /*/
>>> /*Miembro Asesor del Consejo de Epidemiología y Prevención 
>>> Cardiovascular de la SAC*/
>>> /*/
>>> /*/
>>> /*/
>>> /*/
>>> /*Experto en Lipidos de la Sociedad Argentina de Lipidos.*/
>>> /*Miembro de la Sociedad Argentina de Lipidos.*/
>>> /
>>> /*Instructor de ACLS de la American Heart Association*/
>>> /
>>>
>>>
>>> ------------------------------------------------------------------------
>>> *De:* Gerta Ruecker <ruecker using imbi.uni-freiburg.de> 
>>> <mailto:ruecker using imbi.uni-freiburg.de>
>>> *Enviado:* martes, 21 de abril de 2020 14:44
>>> *Para:* Martin Lobo <mlobo4370 using hotmail.com> 
>>> <mailto:mlobo4370 using hotmail.com>; r-sig-meta-analysis using r-project.org 
>>> <mailto:r-sig-meta-analysis using r-project.org> 
>>> <r-sig-meta-analysis using r-project.org> 
>>> <mailto:r-sig-meta-analysis using r-project.org>
>>> *Asunto:* Re: [R-meta] meta analysis with standard deviation or 
>>> standard errors
>>>
>>> Dear Martin,
>>>
>>>
>>> Sorry for the delay. The problem is that the mean and sd of pre and 
>>> post do not suffice to know the sd of the pairwise differences, 
>>> except one makes some assumptions about the intraindividual pre-post 
>>> correlation. See the attached R code PrePost.R for illustration.
>>>
>>>
>>> Do you mean by ri the correlation coefficients? If you impute them 
>>> (say, 0.5), you may analyse the pre-post changes, but you should 
>>> have some (external) evidence for using a certain value.
>>>
>>>
>>> I am not sure about each one of your 5 points below, see inline below.
>>>
>>>
>>> Best,
>>>
>>> Gerta
>>>
>>>
>>>
>>> Am 17.04.2020 um 14:22 schrieb Martin Lobo:
>>>> Thank you very much Gerta.
>>>>
>>>> I asked the question to see how I can solve two problems I have.
>>>>
>>>> 1- If I want to do an metaanalysis of mean difference analysis 
>>>> (Paired data, pre-post)
>>>> I have mean and sd pre and post, what methodd i use, MC , SMCC, etc
>>> What is MC, SMCC? I don't know for what these abbreviations stand. 
>>> Otherwise, see above.
>>>>
>>>> 2- If I only have the mean and standard deviation as I do
>>> See above.
>>>>
>>>> 3 - ri is always necessary or can be imputed in some way
>>> See also above
>>>>
>>>> 4 - without ri the standard deviation of the mean difference can be 
>>>> estimated
>>> Not without knowing or making assumptions about the correlation, as 
>>> said above.
>>>>
>>>> 5 - regarding question 4, both for independent samples and for 
>>>> paired samples
>>>
>>> For independent samples it is different, because for differences of 
>>> independent means we have:
>>>
>>>
>>> sd(X + Y) = sqrt(var(X + Y)) = sqrt(var(X) + var(Y)) = sqrt(sd(X)^2 
>>> + sd(Y)^2)
>>>
>>>
>>> For paired (more general. correlated) variables:
>>>
>>>
>>> sd(X + Y) = sqrt(var(X) + var(Y) - 2Cov(X,Y))
>>>
>>>
>>>>
>>>>
>>>>
>>>> ------------------------------------------------------------------------
>>>> *De:* Gerta Ruecker <ruecker using imbi.uni-freiburg.de> 
>>>> <mailto:ruecker using imbi.uni-freiburg.de>
>>>> *Enviado:* viernes, 17 de abril de 2020 08:12
>>>> *Para:* Martin Lobo <mlobo4370 using hotmail.com> 
>>>> <mailto:mlobo4370 using hotmail.com>; r-sig-meta-analysis using r-project.org 
>>>> <mailto:r-sig-meta-analysis using r-project.org> 
>>>> <r-sig-meta-analysis using r-project.org> 
>>>> <mailto:r-sig-meta-analysis using r-project.org>
>>>> *Asunto:* Re: [R-meta] meta analysis with standard deviation or 
>>>> standard errors
>>>>
>>>> Dear Martin,
>>>>
>>>> The answer is no. The standard error is not a measure of dispersion 
>>>> of the data, but a measure of the imprecision of estimation. A 
>>>> large standard error may come from large variability between data, 
>>>> but also from small sample size. The standard error becomes always 
>>>> small if the sample size becomes large (law of large numbers).
>>>>
>>>> Best,
>>>>
>>>> Gerta
>>>>
>>>> Am 17.04.2020 um 13:07 schrieb Martin Lobo:
>>>>> Hello everyone !
>>>>>
>>>>>
>>>>> I wanted to know if it is possible to use the standard error instead of the standard deviation as a measure of dispersion.
>>>>> using the MD or SMD method for independent samples.
>>>>> If this is possible,  there would be some difference in the conclusions.
>>>>>
>>>>> Thank you so much
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> Lorenzo Mart�n Lobo MTSAC, FACC, FESC
>>>>> Especialista Jerarquizado en Cardiolog�a
>>>>> Jefe de Dpto Enf. Cardiovasculares y Cardiometabolismo Hospital Militar Campo de Mayo.
>>>>> Jefe de Cardiolog�a Hospital Militar Campo de Mayo
>>>>> Ex Jefe de Unidad Coronaria Hospital Militar Campo de Mayo
>>>>> Miembro Titular de la Sociedad Argentina de Cardiolog�a
>>>>> Fellow American College of Cardiology
>>>>> Fellow European Society of Cardiology
>>>>> Ex Miembro del Area de Investigaci�n de la SAC
>>>>> Ex Director del Consejo de Aterosclerosis y Trombosis de la SAC
>>>>> Miembro Asesor del Consejo de Aterosclerosis y Trombosis de la SAC
>>>>> Ex Director del Consejo de Epidemiolog�a y Prevenci�n Cardiovascular de la SAC
>>>>>
>>>>> Miembro Asesor del Consejo de Epidemiolog�a y Prevenci�n Cardiovascular de la SAC
>>>>>
>>>>>
>>>>> Experto en Lipidos de la Sociedad Argentina de Lipidos.
>>>>> Miembro de la Sociedad Argentina de Lipidos.
>>>>> Instructor de ACLS de la American Heart Association
>>>>>
>>>>>
>>>>> ________________________________
>>>>> De: R-sig-meta-analysis<r-sig-meta-analysis-bounces using r-project.org>  <mailto:r-sig-meta-analysis-bounces using r-project.org>  en nombre der-sig-meta-analysis-request using r-project.org  <mailto:r-sig-meta-analysis-request using r-project.org>  <r-sig-meta-analysis-request using r-project.org>  <mailto:r-sig-meta-analysis-request using r-project.org>
>>>>> Enviado: mi�rcoles, 15 de abril de 2020 07:00
>>>>> Para:r-sig-meta-analysis using r-project.org  <mailto:r-sig-meta-analysis using r-project.org>  <r-sig-meta-analysis using r-project.org>  <mailto:r-sig-meta-analysis using r-project.org>
>>>>> Asunto: R-sig-meta-analysis Digest, Vol 35, Issue 8
>>>>>
>>>>> Send R-sig-meta-analysis mailing list submissions to
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>>>>>
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>>>>>
>>>>>
>>>>> Today's Topics:
>>>>>
>>>>>     1. Re: Dear Wolfgang (Viechtbauer, Wolfgang (SP))
>>>>>     2. Re: Dear Wolfgang (Ju Lee)
>>>>>
>>>>> ----------------------------------------------------------------------
>>>>>
>>>>> Message: 1
>>>>> Date: Tue, 14 Apr 2020 20:43:51 +0000
>>>>> From: "Viechtbauer, Wolfgang (SP)"
>>>>>          <wolfgang.viechtbauer using maastrichtuniversity.nl>  <mailto:wolfgang.viechtbauer using maastrichtuniversity.nl>
>>>>> To: Ju Lee<juhyung2 using stanford.edu>  <mailto:juhyung2 using stanford.edu>,
>>>>>          "r-sig-meta-analysis using r-project.org"  <mailto:r-sig-meta-analysis using r-project.org>
>>>>>          <r-sig-meta-analysis using r-project.org>  <mailto:r-sig-meta-analysis using r-project.org>
>>>>> Subject: Re: [R-meta] Dear Wolfgang
>>>>> Message-ID:<b411740819d1411da87d505cdeceb3e6 using UM-MAIL3214.unimaas.nl>  <mailto:b411740819d1411da87d505cdeceb3e6 using UM-MAIL3214.unimaas.nl>
>>>>> Content-Type: text/plain; charset="iso-8859-1"
>>>>>
>>>>> Yes, if the effect size measure is the same, one can make such a comparison. Also, there should not be any overlap in the studies included in the two meta-analyses (as otherwise the two estimates are not independent, as assumed by the test). And yes, you don't need sample sizes or tau^2 values or anything else - just the two estimates and their corresponding standard errors. And it doesn't depend on what random effects structure was used in the two meta-analyses -- assuming that the structures used in the two meta-analyses were appropriate for the studies at hand.
>>>>>
>>>>> Best,
>>>>> Wolfgang
>>>>>
>>>>>> -----Original Message-----
>>>>>> From: Ju Lee [mailto:juhyung2 using stanford.edu]
>>>>>> Sent: Tuesday, 14 April, 2020 18:54
>>>>>> To: Viechtbauer, Wolfgang (SP);r-sig-meta-analysis using r-project.org  <mailto:r-sig-meta-analysis using r-project.org>
>>>>>> Subject: Re: Dear Wolfgang
>>>>>>
>>>>>> Dear Wolfgang,
>>>>>>
>>>>>> Thanks for your insights.
>>>>>> I am reaching out to my colleagues to see how they have made such
>>>>>> transformation.
>>>>>>
>>>>>> In the meantime, based on the information that you have sent, it is possible
>>>>>> to compare two different meta-analyses if they are using the same effect
>>>>>> size, say lnRR? and this wald-type test can be performed only with grand
>>>>>> mean effect sizes and their standard error, without sample sizes or tau
>>>>>> value, if I understood correctly?
>>>>>>
>>>>>> How would this approach be actually applicable to publications that
>>>>>> seemingly used similar mixed-effect models but there is no guarantee that
>>>>>> random effect structures are standardized between the two?
>>>>>>
>>>>> [[elided Hotmail spam]]
>>>>>> Best,
>>>>>> JU
>>>>>> ________________________________________
>>>>>> From: Viechtbauer, Wolfgang (SP)
>>>>>> <wolfgang.viechtbauer using maastrichtuniversity.nl>  <mailto:wolfgang.viechtbauer using maastrichtuniversity.nl>
>>>>>> Sent: Tuesday, April 14, 2020 7:04 AM
>>>>>> To: Ju Lee<juhyung2 using stanford.edu>  <mailto:juhyung2 using stanford.edu>;r-sig-meta-analysis using r-project.org  <mailto:r-sig-meta-analysis using r-project.org>  <r-
>>>>>> sig-meta-analysis using r-project.org  <mailto:sig-meta-analysis using r-project.org>>
>>>>>> Subject: RE: Dear Wolfgang
>>>>>>
>>>>>> Dear Ju,
>>>>>>
>>>>>> In principle, this might be of interest to you:
>>>>>>
>>>>>> https://nam01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.metafor-project.org%2Fdoku.php%2Ftips%3Acomp_two_independent_estimates&data=02%7C01%7C%7C7f93a72da7b64707fe6d08d7e12439ac%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637225418004815037&sdata=Tqgh0WpvUo70JTaihNWcZcbVQCQRpbprCYAxGKtlBGY%3D&reserved=0  <https://eur05.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.metafor-project.org%2Fdoku.php%2Ftips%3Acomp_two_independent_estimates&data=02%7C01%7C%7C50bd0edfa39a4d34702f08d7e6c7caeb%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637231618285623034&sdata=XsMRHy8lut9U%2FXh%2BsIqcZ%2BvghN2%2FQrsxNXGnv6bJa5Y%3D&reserved=0>
>>>>>>
>>>>>> However, a standardized mean difference is given by (m1-m2)/sd, while a
>>>>>> (log) response ratio is log(m1/m2). I see no sensible way of converting the
>>>>>> former to the later.
>>>>>>
>>>>>> Best,
>>>>>> Wolfgang
>>>>>>
>>>>>>> -----Original Message-----
>>>>>>> From: R-sig-meta-analysis [mailto:r-sig-meta-analysis-bounces using r-
>>>>>> project.org]
>>>>>>> On Behalf Of Ju Lee
>>>>>>> Sent: Monday, 13 April, 2020 22:47
>>>>>>> To:r-sig-meta-analysis using r-project.org  <mailto:r-sig-meta-analysis using r-project.org>
>>>>>>> Subject: [R-meta] Dear Wolfgang
>>>>>>>
>>>>>>> Dear Wolfgang,
>>>>>>>
>>>>>>> I hope you are doing well.
>>>>>>>
>>>>>>> My research group is currently working on a project where they are trying
>>>>>> to
>>>>>>> compare effect sizes generated from their current mixed-effect meta-
>>>>>> analysis
>>>>>>> with effect sizes (based on similar response variables) calculated in other
>>>>>>> meta-analysis publications.
>>>>>>>
>>>>>>> We are currently using log response ratio and are trying to make some
>>>>>>> statement or analysis to compare our grand mean effect sizes with other
>>>>>>> studies. In more details, we are examining how herbivorous animal control
>>>>>>> plant growth in degraded environment. Now, there is already a meta-analysis
>>>>>>> out there that has examined this (in comparable manner) in natural
>>>>>>> environment as opposed to our study.
>>>>>>>
>>>>>>> My colleagues want to know if there is a way to make some type of
>>>>>> comparison
>>>>>>> (ex. whether responses are stronger in degraded vs. natural environemnts)
>>>>>>> between two effect sizes from these different studies using statistical
>>>>>>> approaches.
>>>>>>> So far what they have from other meta-analysis publication is grand mean
>>>>>>> hedges'd and var which they transformed to lnRR and var in hopes to compare
>>>>>>> with our lnRR effect sizes.
>>>>>>>
>>>>>>> My view is that this is not possible unless we can have their actual raw
>>>>>>> dataset and run a whole new model combining with our original raw dataset.
>>>>>>> But I wanted to reach out to you and the community  if there is an
>>>>>>> alternative approaches to compare mean effect sizes among different meta-
>>>>>>> analysis which are assumed to have used similar approaches in study
>>>>>>> selection and models (another issue being different random effect
>>>>>> structures
>>>>>>> used in different meta-analysis which may not be very apparent from method
>>>>>>> description).
>>>>>>>
>>>>> [[elided Hotmail spam]]
>>>>>>> Best,
>>>>>>> JU
>>>>> ------------------------------
>>>>>
>>>>> Message: 2
>>>>> Date: Wed, 15 Apr 2020 05:33:16 +0000
>>>>> From: Ju Lee<juhyung2 using stanford.edu>  <mailto:juhyung2 using stanford.edu>
>>>>> To: "Viechtbauer, Wolfgang (SP)"
>>>>>          <wolfgang.viechtbauer using maastrichtuniversity.nl>  <mailto:wolfgang.viechtbauer using maastrichtuniversity.nl>,
>>>>>          "r-sig-meta-analysis using r-project.org"  <mailto:r-sig-meta-analysis using r-project.org>
>>>>>          <r-sig-meta-analysis using r-project.org>  <mailto:r-sig-meta-analysis using r-project.org>
>>>>> Subject: Re: [R-meta] Dear Wolfgang
>>>>> Message-ID:
>>>>>          <BYAPR02MB5559407370455A06F0B047A8F7DB0 using BYAPR02MB5559.namprd02.prod.outlook.com>  <mailto:BYAPR02MB5559407370455A06F0B047A8F7DB0 using BYAPR02MB5559.namprd02.prod.outlook.com>
>>>>>
>>>>> Content-Type: text/plain; charset="utf-8"
>>>>>
>>>>> Dear Wolfgang,
>>>>>
>>>>> [[elided Hotmail spam]]
>>>>> I am not sure how my colleagues have transformed hedges' d to lnRR, based on what sources, but I will reach out again once I have more details. I, too, have not known if there is a way to make such effect size transformation.
>>>>>
>>>>> Thank you very much!
>>>>> Best wishes,
>>>>> JU
>>>>> ________________________________
>>>>> From: Viechtbauer, Wolfgang (SP)<wolfgang.viechtbauer using maastrichtuniversity.nl>  <mailto:wolfgang.viechtbauer using maastrichtuniversity.nl>
>>>>> Sent: Tuesday, April 14, 2020 1:43 PM
>>>>> To: Ju Lee<juhyung2 using stanford.edu>  <mailto:juhyung2 using stanford.edu>;r-sig-meta-analysis using r-project.org  <mailto:r-sig-meta-analysis using r-project.org>  <r-sig-meta-analysis using r-project.org>  <mailto:r-sig-meta-analysis using r-project.org>
>>>>> Subject: RE: Dear Wolfgang
>>>>>
>>>>> Yes, if the effect size measure is the same, one can make such a comparison. Also, there should not be any overlap in the studies included in the two meta-analyses (as otherwise the two estimates are not independent, as assumed by the test). And yes, you don't need sample sizes or tau^2 values or anything else - just the two estimates and their corresponding standard errors. And it doesn't depend on what random effects structure was used in the two meta-analyses -- assuming that the structures used in the two meta-analyses were appropriate for the studies at hand.
>>>>>
>>>>> Best,
>>>>> Wolfgang
>>>>>
>>>>>> -----Original Message-----
>>>>>> From: Ju Lee [mailto:juhyung2 using stanford.edu]
>>>>>> Sent: Tuesday, 14 April, 2020 18:54
>>>>>> To: Viechtbauer, Wolfgang (SP);r-sig-meta-analysis using r-project.org  <mailto:r-sig-meta-analysis using r-project.org>
>>>>>> Subject: Re: Dear Wolfgang
>>>>>>
>>>>>> Dear Wolfgang,
>>>>>>
>>>>>> Thanks for your insights.
>>>>>> I am reaching out to my colleagues to see how they have made such
>>>>>> transformation.
>>>>>>
>>>>>> In the meantime, based on the information that you have sent, it is possible
>>>>>> to compare two different meta-analyses if they are using the same effect
>>>>>> size, say lnRR? and this wald-type test can be performed only with grand
>>>>>> mean effect sizes and their standard error, without sample sizes or tau
>>>>>> value, if I understood correctly?
>>>>>>
>>>>>> How would this approach be actually applicable to publications that
>>>>>> seemingly used similar mixed-effect models but there is no guarantee that
>>>>>> random effect structures are standardized between the two?
>>>>>>
>>>>> [[elided Hotmail spam]]
>>>>>> Best,
>>>>>> JU
>>>>>> ________________________________________
>>>>>> From: Viechtbauer, Wolfgang (SP)
>>>>>> <wolfgang.viechtbauer using maastrichtuniversity.nl>  <mailto:wolfgang.viechtbauer using maastrichtuniversity.nl>
>>>>>> Sent: Tuesday, April 14, 2020 7:04 AM
>>>>>> To: Ju Lee<juhyung2 using stanford.edu>  <mailto:juhyung2 using stanford.edu>;r-sig-meta-analysis using r-project.org  <mailto:r-sig-meta-analysis using r-project.org>  <r-
>>>>>> sig-meta-analysis using r-project.org  <mailto:sig-meta-analysis using r-project.org>>
>>>>>> Subject: RE: Dear Wolfgang
>>>>>>
>>>>>> Dear Ju,
>>>>>>
>>>>>> In principle, this might be of interest to you:
>>>>>>
>>>>>> https://nam01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.metafor-project.org%2Fdoku.php%2Ftips%3Acomp_two_independent_estimates&data=02%7C01%7C%7C7f93a72da7b64707fe6d08d7e12439ac%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637225418004815037&sdata=Tqgh0WpvUo70JTaihNWcZcbVQCQRpbprCYAxGKtlBGY%3D&reserved=0  <https://eur05.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.metafor-project.org%2Fdoku.php%2Ftips%3Acomp_two_independent_estimates&data=02%7C01%7C%7C50bd0edfa39a4d34702f08d7e6c7caeb%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637231618285623034&sdata=XsMRHy8lut9U%2FXh%2BsIqcZ%2BvghN2%2FQrsxNXGnv6bJa5Y%3D&reserved=0>
>>>>>>
>>>>>> However, a standardized mean difference is given by (m1-m2)/sd, while a
>>>>>> (log) response ratio is log(m1/m2). I see no sensible way of converting the
>>>>>> former to the later.
>>>>>>
>>>>>> Best,
>>>>>> Wolfgang
>>>>>>
>>>>>>> -----Original Message-----
>>>>>>> From: R-sig-meta-analysis [mailto:r-sig-meta-analysis-bounces using r-
>>>>>> project.org]
>>>>>>> On Behalf Of Ju Lee
>>>>>>> Sent: Monday, 13 April, 2020 22:47
>>>>>>> To:r-sig-meta-analysis using r-project.org  <mailto:r-sig-meta-analysis using r-project.org>
>>>>>>> Subject: [R-meta] Dear Wolfgang
>>>>>>>
>>>>>>> Dear Wolfgang,
>>>>>>>
>>>>>>> I hope you are doing well.
>>>>>>>
>>>>>>> My research group is currently working on a project where they are trying
>>>>>> to
>>>>>>> compare effect sizes generated from their current mixed-effect meta-
>>>>>> analysis
>>>>>>> with effect sizes (based on similar response variables) calculated in other
>>>>>>> meta-analysis publications.
>>>>>>>
>>>>>>> We are currently using log response ratio and are trying to make some
>>>>>>> statement or analysis to compare our grand mean effect sizes with other
>>>>>>> studies. In more details, we are examining how herbivorous animal control
>>>>>>> plant growth in degraded environment. Now, there is already a meta-analysis
>>>>>>> out there that has examined this (in comparable manner) in natural
>>>>>>> environment as opposed to our study.
>>>>>>>
>>>>>>> My colleagues want to know if there is a way to make some type of
>>>>>> comparison
>>>>>>> (ex. whether responses are stronger in degraded vs. natural environemnts)
>>>>>>> between two effect sizes from these different studies using statistical
>>>>>>> approaches.
>>>>>>> So far what they have from other meta-analysis publication is grand mean
>>>>>>> hedges'd and var which they transformed to lnRR and var in hopes to compare
>>>>>>> with our lnRR effect sizes.
>>>>>>>
>>>>>>> My view is that this is not possible unless we can have their actual raw
>>>>>>> dataset and run a whole new model combining with our original raw dataset.
>>>>>>> But I wanted to reach out to you and the community  if there is an
>>>>>>> alternative approaches to compare mean effect sizes among different meta-
>>>>>>> analysis which are assumed to have used similar approaches in study
>>>>>>> selection and models (another issue being different random effect
>>>>>> structures
>>>>>>> used in different meta-analysis which may not be very apparent from method
>>>>>>> description).
>>>>>>>
>>>>> [[elided Hotmail spam]]
>>>>>>> Best,
>>>>>>> JU
>>>>>          [[alternative HTML version deleted]]
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> ------------------------------
>>>>>
>>>>> Subject: Digest Footer
>>>>>
>>>>> _______________________________________________
>>>>> R-sig-meta-analysis mailing list
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>>>>>
>>>>>
>>>>> ------------------------------
>>>>>
>>>>> End of R-sig-meta-analysis Digest, Vol 35, Issue 8
>>>>> **************************************************
>>>>>
>>>>> 	[[alternative HTML version deleted]]
>>>>>
>>>>>
>>>>> _______________________________________________
>>>>> R-sig-meta-analysis mailing list
>>>>> R-sig-meta-analysis using r-project.org  <mailto:R-sig-meta-analysis using r-project.org>
>>>>> https://stat.ethz.ch/mailman/listinfo/r-sig-meta-analysis  <https://eur05.safelinks.protection.outlook.com/?url=https%3A%2F%2Fstat.ethz.ch%2Fmailman%2Flistinfo%2Fr-sig-meta-analysis&data=02%7C01%7C%7C50bd0edfa39a4d34702f08d7e6c7caeb%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637231618285633029&sdata=WhIMmdiH5enBQRuU%2BEtUCylbsZSfK2ZBTqm0p%2B%2BsgmE%3D&reserved=0>
>>>> -- 
>>>>
>>>> Dr. rer. nat. Gerta Rücker, Dipl.-Math.
>>>>
>>>> Institute of Medical Biometry and Statistics,
>>>> Faculty of Medicine and Medical Center - University of Freiburg
>>>>
>>>> Stefan-Meier-Str. 26, D-79104 Freiburg, Germany
>>>>
>>>> Phone:    +49/761/203-6673
>>>> Fax:      +49/761/203-6680
>>>> Mail:ruecker using imbi.uni-freiburg.de  <mailto:ruecker using imbi.uni-freiburg.de>
>>>> Homepage:https://www.imbi.uni-freiburg.de/persons/ruecker/person_view  <https://eur05.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.imbi.uni-freiburg.de%2Fpersons%2Fruecker%2Fperson_view&data=02%7C01%7C%7C50bd0edfa39a4d34702f08d7e6c7caeb%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637231618285643023&sdata=unn63E9aAWHY7dFlimdVsbN5AsXlryiYsifTVPliwb4%3D&reserved=0>
>>> -- 
>>>
>>> Dr. rer. nat. Gerta Rücker, Dipl.-Math.
>>>
>>> Institute of Medical Biometry and Statistics,
>>> Faculty of Medicine and Medical Center - University of Freiburg
>>>
>>> Stefan-Meier-Str. 26, D-79104 Freiburg, Germany
>>>
>>> Phone:    +49/761/203-6673
>>> Fax:      +49/761/203-6680
>>> Mail:ruecker using imbi.uni-freiburg.de  <mailto:ruecker using imbi.uni-freiburg.de>
>>> Homepage:https://www.imbi.uni-freiburg.de/persons/ruecker/person_view  <https://eur05.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.imbi.uni-freiburg.de%2Fpersons%2Fruecker%2Fperson_view&data=02%7C01%7C%7C50bd0edfa39a4d34702f08d7e6c7caeb%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637231618285643023&sdata=unn63E9aAWHY7dFlimdVsbN5AsXlryiYsifTVPliwb4%3D&reserved=0>
>> -- 
>>
>> Dr. rer. nat. Gerta Rücker, Dipl.-Math.
>>
>> Institute of Medical Biometry and Statistics,
>> Faculty of Medicine and Medical Center - University of Freiburg
>>
>> Stefan-Meier-Str. 26, D-79104 Freiburg, Germany
>>
>> Phone:    +49/761/203-6673
>> Fax:      +49/761/203-6680
>> Mail:ruecker using imbi.uni-freiburg.de  <mailto:ruecker using imbi.uni-freiburg.de>
>> Homepage:https://www.imbi.uni-freiburg.de/persons/ruecker/person_view  <https://eur05.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.imbi.uni-freiburg.de%2Fpersons%2Fruecker%2Fperson_view&data=02%7C01%7C%7C50bd0edfa39a4d34702f08d7e6c7caeb%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637231618285643023&sdata=unn63E9aAWHY7dFlimdVsbN5AsXlryiYsifTVPliwb4%3D&reserved=0>
> -- 
>
> Dr. rer. nat. Gerta Rücker, Dipl.-Math.
>
> Institute of Medical Biometry and Statistics,
> Faculty of Medicine and Medical Center - University of Freiburg
>
> Stefan-Meier-Str. 26, D-79104 Freiburg, Germany
>
> Phone:    +49/761/203-6673
> Fax:      +49/761/203-6680
> Mail:ruecker using imbi.uni-freiburg.de  <mailto:ruecker using imbi.uni-freiburg.de>
> Homepage:https://www.imbi.uni-freiburg.de/persons/ruecker/person_view  <https://eur05.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.imbi.uni-freiburg.de%2Fpersons%2Fruecker%2Fperson_view&data=02%7C01%7C%7C50bd0edfa39a4d34702f08d7e6c7caeb%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637231618285653020&sdata=raYwUS8%2FSRV1x6fzwZe%2B%2FmCFMzghHsoOUPuiVsZK2H0%3D&reserved=0>

-- 

Dr. rer. nat. Gerta Rücker, Dipl.-Math.

Institute of Medical Biometry and Statistics,
Faculty of Medicine and Medical Center - University of Freiburg

Stefan-Meier-Str. 26, D-79104 Freiburg, Germany

Phone:    +49/761/203-6673
Fax:      +49/761/203-6680
Mail:     ruecker using imbi.uni-freiburg.de
Homepage: https://www.imbi.uni-freiburg.de/persons/ruecker/person_view


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