[R-meta] rma.mv only for better SEs

[Viechtbauer, Wolfgang (SP)]

Right, sorry, that was a typo.

Best,
Wolfgang

>-----Original Message-----
>From: Simon Harmel [mailto:sim.harmel using gmail.com]
>Sent: Monday, 31 January, 2022 19:29
>To: Viechtbauer, Wolfgang (SP)
>Cc: R meta
>Subject: Re: [R-meta] rma.mv only for better SEs
>
>Sure, but didn't you by any chance mean to say:
>"The random effects structure determines the weight matrix, which in turn affects
>the estimates of the **fixed effects**".
>
>On Mon, Jan 31, 2022 at 12:23 PM Viechtbauer, Wolfgang (SP)
><wolfgang.viechtbauer using maastrichtuniversity.nl> wrote:
>The random effects structure determines the weight matrix, which in turn affects
>the estimates of the random effects.
>
>Best,
>Wolfgang
>
>>-----Original Message-----
>>From: Simon Harmel [mailto:sim.harmel using gmail.com]
>>Sent: Monday, 31 January, 2022 18:29
>>To: Viechtbauer, Wolfgang (SP)
>>Cc: R meta
>>Subject: Re: [R-meta] rma.mv only for better SEs
>>
>>I have done it, and in my case the results differ. But my point was, is my
>>explanation regarding why they differ accurate?
>>
>>On Mon, Jan 31, 2022 at 11:24 AM Viechtbauer, Wolfgang (SP)
>><wolfgang.viechtbauer using maastrichtuniversity.nl> wrote:
>>Just try it out and you will see what happens.
>>
>>Best,
>>Wolfgang
>>
>>>-----Original Message-----
>>>From: Simon Harmel [mailto:sim.harmel using gmail.com]
>>>Sent: Monday, 31 January, 2022 18:21
>>>To: Viechtbauer, Wolfgang (SP)
>>>Cc: R meta
>>>Subject: Re: [R-meta] rma.mv only for better SEs
>>>
>>>Thank you, Wolfgang. I asked this, because I noticed applying RVE to an
>rma.mv()
>>>model has no bearing on the estimates of fixed effects themselves, and just
>>>modifies their SEs.
>>>
>>>So, I wondered if the same rule, at least "in principle", should apply when we
>>go
>>>from rma() to rma.mv().
>>>
>>>But is there a principle regarding how random effects affect the fixed effects?
>>>
>>>For instance, in:
>>>
>>>1- rma.mv(y ~ 1, random = ~ 1|study/obs), the overall average only represents
>>the
>>>average of study-level effects.
>>>
>>>But, in:
>>>
>>>2- rma.mv(y ~ 1, random = ~ 1|study/outcome/obs), the overall average
>represents
>>>the average of study-level effects additionally affected by the outcome-level
>>>effects within them.
>>>
>>>And thus, 1- and 2- may give different overall averages, right?
>>>
>>>Simon
>>>
>>>On Mon, Jan 31, 2022 at 11:00 AM Viechtbauer, Wolfgang (SP)
>>><wolfgang.viechtbauer using maastrichtuniversity.nl> wrote:
>>>Generally, two models with different random effects structures will also give
>>you
>>>different estimates of the fixed effects (unless the estimates of the
>>>variance/covariance components happen to be such that the two models collapse
>>>down to the same structure).
>>>
>>>Best,
>>>Wolfgang
>>>
>>>>-----Original Message-----
>>>>From: R-sig-meta-analysis [mailto:r-sig-meta-analysis-bounces using r-project.org]
>On
>>>>Behalf Of Simon Harmel
>>>>Sent: Monday, 31 January, 2022 17:49
>>>>To: R meta
>>>>Subject: [R-meta] rma.mv only for better SEs
>>>>
>>>>Hello List Members,
>>>>
>>>>Reviewing the archived posts, my understanding is that my studies can
>>>>produce multiple effects, so I should use rma.mv() not rma().
>>>>
>>>>Also, I understand rma.mv() ensures that I get more accurate SEs for my
>>>>fixed effects relative to rma().
>>>>
>>>>BUT does that also mean that, by definition, rma.mv() should have no
>>>>bearing on the magnitude of the fixed effects themselves and only modifies
>>>>their SEs relative to rma()?
>>>>
>>>>Thank you,
>>>>Simon