[R-sig-ME] How to specify user-defined matrix Z?

Zhengyang Zhou Zhengyang.Zhou at UTSouthwestern.edu
Thu Sep 28 22:15:21 CEST 2017

?Hi all,

In genetic studies, we sometimes include the genetic relatedness matrix as a variance component, so we have this following model:

where beta are the fixed effects, b~N(0,sigma^2*I) are the random effects, error are the random error, Z is the cholesky decomposition of the known genetic relatedness matrix. So how to use lme4 to fit this model if we know X and Z beforehand? I can use the package "nlme" to do it using the code like

lme(y~-1+X, random=list(group=pdIdent(~-1+Z))),
but how to do it using lme4?

(It's my first time to submit a post, and please let me know if I made anything wrong/inproper.)

Thank you.


UT Southwestern

Medical Center

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