[R-sig-ME] R-sig-mixed-models Digest, Vol 136, Issue 41

Maarten Jung Maarten.Jung at mailbox.tu-dresden.de
Tue May 1 15:45:20 CEST 2018

Dear Rune,

am I right in thinking of Model3b as a zero-correlation-parameter
model (m_zcp) but with the variances of the operators-related effects
constrained to equality?
Specifically, is the difference between Model3b and m_zcp that m_zcp
estimates variance components for each level of the factor 'machines'
and Model3b assumes equal variances across the levels of machines and
estimates only one variance for all levels?

Model3b <- lmer(Y ~ machines + (1 | operators) + (1 | machines:operators))
m_zcp  <- lmer(Y ~ machines + (machines || operators))


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