I constructed two models with
decomposition ~ trait1 + trait2 + trait3 + (1|pair)
all trait effects are highly significant
yet when I run this simplified model:
decomposition ~ trait1 + trait2 + (1|pair)
the effect of
trait1 is not significant,
trait2 is significant.
How is this possible and what can I conclude about the effect of
I have 50 observations, if that matters.
Can this be due to model assumptions that are not met? I visually checked for homoscedasticity and did a formal test for normality of residuals, which appear to be fine though.