[R-meta] mods~factor

[Viechtbauer, Wolfgang (SP)]

Dear Angelo,

The factor() function is not something from metafor, but is part of R itself.

String variables are automatically converted to factors, so using factor() on them doesn't change anything.

As for the interpretation of results when including factor variables in models, see:

https://www.metafor-project.org/doku.php/tips:models_with_or_without_intercept

Best,
Wolfgang

>-----Original Message-----
>From: R-sig-meta-analysis [mailto:r-sig-meta-analysis-bounces using r-project.org] On
>Behalf Of angelo solarino
>Sent: Tuesday, 29 June, 2021 12:21
>To: r-sig-meta-analysis using r-project.org
>Subject: [R-meta] mods~factor
>
>DA,
>
>I am having some trouble with the "factor" command in metafor.
>I am not able to get the split for the variable field. it is a string
>value. whether i add "mods~factor(field)"  or not I get the same main
>effect results, and there is no error message. Can anyone help me figure
>out what I am doing wrong?
>
>res <- rma(yi,vi, mods~factor(field), data=Outcomes1, method = "HS",
>subset=(ID=="XX" | ID=="XY"))
>
>Thanks a lot for your help,
>Angelo