[R-meta] Interpreting splines in 'rma' models

[Viechtbauer, Wolfgang (SP)]

Hi Cort,

That link got a bit mangled -- it should be this one:

https://stats.stackexchange.com/questions/279668/meta-regression-using-restricted-cubic-splines-with-rma-from-the-metafor-pack

I would suggest to take a look at Frank Harrell's book (Regression Modeling Strategies). Chapter 2 explains how the variables making up the function are constructed and that clarifies the interpretation of the corresponding coefficients (although as far as I am concerned, the interpretation of the specific terms isn't entirely trivial).

Best,
Wolfgang

-----Original Message-----
From: R-sig-meta-analysis [mailto:r-sig-meta-analysis-bounces at r-project.org] On Behalf Of Cort Rudolph
Sent: Thursday, 10 May, 2018 22:32
To: r-sig-meta-analysis at r-project.org
Subject: [R-meta] Interpreting splines in 'rma' models

Dear All,

I have a question about interpreting parameters resulting from an 'rma' model that includes a regression spline. Dr. Viechtbauer covers how to specify such models here: https://stats.stackexchange.com/questions/279668/meta-regression-using-restricted-cubic-splines-with-rma-from-the-metafor-pack<https://urldefense.proofpoint.com/v2/url?u=https-3A__stats.stackexchange.com_questions_279668_meta-2Dregression-2Dusing-2Drestricted-2Dcubic-2Dsplines-2Dwith-2Drma-2Dfrom-2Dthe-2Dmetafor-2Dpack&d=DwMFAw&c=Pk_HpaIpE_jAoEC9PLIWoQ&r=rNX1UkCxUQfEMT5qhA7h1S6aeVyJogKJSz4W2QP2vaM&m=qQJoZc4w5ugutv_h2dOPzbQDaQb4k0DGEz6xWmnh8x0&s=DFKavcmM9SCKe-wE5ggD3BMq2jw4D-Wp-3G3ISxbjg8&e=>

Considering this example, I am hung up on how to interpret the resulting parameters in the 'res' model object created by this 'rma' model.

Any thoughts on this would be very helpful!

Cheers,

Cort.

Cort W. Rudolph, Ph.D.
Assistant Professor
Industrial and Organizational Psychology
Saint Louis University
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