# [R-meta] rma.mv-When a higher level can't be modeled because of one row

Viechtbauer, Wolfgang (SP) wo||g@ng@v|echtb@uer @end|ng |rom m@@@tr|chtun|ver@|ty@n|
Mon Nov 8 11:12:59 CET 2021

```Dear Fred,

I would consider using measure as a fixed effect or making it nested within study (or within outcome). But none of this might really be appropriate for a dataset this small (but I assume this was just constructed for illustrating your question).

Best,
Wolfgang

>-----Original Message-----
>From: Farzad Keyhan [mailto:f.keyhaniha using gmail.com]
>Sent: Friday, 05 November, 2021 2:59
>To: R meta
>Cc: Viechtbauer, Wolfgang (SP)
>Subject: Re: rma.mv-When a higher level can't be modeled because of one row
>
>For clarity, by a solution, I mean how can I account for the
>heterogeneity in true effects attributable to "measure", while
>"measure" is neither a perfect candidate for being the nestor of
>study:
>
>random = ~1 | measure/study/outcome
>
>nor a perfect candidate for being crossed with study:
>
>random = list(~1 | study/outcome, ~1|measure)
>
>Thank you,
>Fred
>
>On Thu, Nov 4, 2021 at 2:26 PM Farzad Keyhan <f.keyhaniha using gmail.com> wrote:
>>
>> Dear Experts,
>>
>> In my toy data below, if in row # 3, "measure" was 2 (instead of 1),
>> then, I could take "measure" as a level higher than study:
>>
>> random = ~1 | measure/study/outcome
>>
>> But right now, because in study 2 (rows # 3 and 4) "measure" can vary,
>> "measure" can't be considered a level higher than study.
>>
>> On the other hand, because "measure" varies only in one study, I can't
>> take "measure" as a crossed random-effect either.
>>
>> I was wondering what solutions the expert list members might have for
>> this situation?
>>
>> Thanks,
>> Fred
>>
>>    measure       row   study   outcome
>>    1             1     1       1
>>    1             2     1       2
>> #  1             3     2       1 <--- measure on this row
>>    2             4     2       1
>>    1             5     3       1
>>    1             6     3       2
```