3
$\begingroup$

I'm trying to get the specification correct for a crossed and nested effect model. Suppose I want to cross Sample & typeStatus, and then have a random effect of day nested within that cross?

I've been trying to figure it out from Ch2 (pdf) of the online book, lme4: Mixed-effects Modeling with R, but can't quite seem to get it.

$\endgroup$

1 Answer 1

2
$\begingroup$

The pdf lists an example of fitting a model with crossed random effects using the Penicillin dataset in section 2.1.2 (p. 4 of pdf), and an example of fitting a model with nested random effects using the Pastes dataset in section 2.2.2 (p. 14 of pdf). At the beginning of the latter section, it reads:

Fitting a model with simple, scalar random effects for nested factors is done in exactly the same way as fitting a model with random effects for crossed grouping factors.

I don't know much about your data, but from these I would guess that you might specify your model like so:

library(lme4)
model = lmer(y ~ 1 + covariates + (1|Sample) + (1|typeStatus) + (1|day), data=myData)  
$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.