<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40"><head><meta http-equiv=Content-Type content="text/html; charset=iso-8859-1"><meta name=Generator content="Microsoft Word 15 (filtered medium)"><style><!--
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</o:shapelayout></xml><![endif]--></head><body lang=DE link="#0563C1" vlink="#954F72"><div class=WordSection1><p class=MsoNormal><span style='font-family:"Times New Roman",serif'>Hi all,<o:p></o:p></span></p><p class=MsoNormal><span style='font-family:"Times New Roman",serif'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-family:"Times New Roman",serif'>I am currently investigating the possibility of assessing non-linear effects in a meta-regression.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-family:"Times New Roman",serif'>For example, I am interested in the relationship between risk-taking and performance, and I want to assess whether the mean score of risk taking has a non-linear moderating effect on that relationship.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-family:"Times New Roman",serif'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-family:"Times New Roman",serif'>I had a look at Wolfgang’s previous examples on adding restricted cubic splines to mixed effects models via the rms package e.g. <o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-family:"Times New Roman",serif'><a href="https://stats.stackexchange.com/questions/279668/meta-regression-using-restricted-cubic-splines-with-rma-from-the-metafor-pack?rq=1">https://stats.stackexchange.com/questions/279668/meta-regression-using-restricted-cubic-splines-with-rma-from-the-metafor-pack?rq=1</a><o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-family:"Times New Roman",serif'><a href="https://stat.ethz.ch/pipermail/r-sig-meta-analysis/2018-February/000551.html">https://stat.ethz.ch/pipermail/r-sig-meta-analysis/2018-February/000551.html</a> <o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-family:"Times New Roman",serif'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-family:"Times New Roman",serif'>and looked a bit into Frank Harrell’s book concerning the adequate number and location of nodes.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-family:"Times New Roman",serif'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-family:"Times New Roman",serif'>My question now is, how do I determine/test whether the plotted spline is actually significant/meaningful?<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-family:"Times New Roman",serif'>I am a bit unsure what I should make of the mixed effects model results in that regard or if I have to perform additional tests.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-family:"Times New Roman",serif'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-family:"Times New Roman",serif'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-family:"Times New Roman",serif'>Best<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-family:"Times New Roman",serif'>Jens<o:p></o:p></span></p></div></body></html>