-----Original Message-----
From: R-sig-meta-analysis [mailto:r-sig-meta-analysis-bounces at r-project.org] On
Behalf Of YA
Sent: Wednesday, 02 February, 2022 5:34
To: r-sig-meta-analysis
Subject: Re: [R-meta] Meta-analysis of mean differences
Hi Martin and others,
What about the three level meta-analysis?
Level 1: effect size between ctrl and exp group (ie, cohen's d or hedges' g),
which are nested within
Level 2: groups of the effect size (ie, pretest or posttest, or t1, t2, t3....),
which are nested within
Level 3: studies.
In this way, you dont need to know the correlations between the pre and post test
or among time points, the correlations are controlled for by involving a level 2,
just like the control of the dependency in multilevel modeling.
hope this helpful.
YA
------------------ Original ------------------
From: "Martin Lobo" <mlobo4370 at hotmail.com>;
Date: Tue, Feb 1, 2022 09:40 PM
To: "Michael Dewey"<lists at dewey.myzen.co.uk>;"Viechtbauer, Wolfgang
(SP)"<wolfgang.viechtbauer at maastrichtuniversity.nl>;"r-sig-meta-analysis at r-
project.org"<r-sig-meta-analysis at r-project.org>;"Gerta
Ruecker"<ruecker at imbi.uni-freiburg.de>;
Subject: Re: [R-meta] Meta-analysis of mean differences
Hello, thank you all.
I don't quite understand how to test different sensitivity analyzes with
different correlation coefficients. What had occurred to me was to use the values
??after the intervention in the two groups and do a meta-regression using the
baseline LDL level as a covariate, and thus adjust the result for it, but I don't
know if that would be correct.
In any case, I want to explain the case again, since out there it was interpreted
as paired measurements and it is not.
I have group A and Group B, in each group I have a baseline value of LDL and the
value after the intervention, and I need to meta-analyze the impact on this
variable. I usually do it already having the difference between baseline and
post-treatment of the two groups with their deviations, but in this case I only
have these data to make a difference of means. That's why I also asked how to do
it with change scores, something like that had been explained to me by gerta but
I didn't understand.
Thanks a lot
Lorenzo Mart?n Lobo MTSAC, FACC, FESC
Especialista Jerarquizado en Cardiolog?a