I have found a web page telling that for lmer:
If your random effects are nested, or you have only one random effect, and if your data are balanced (i.e., similar sample sizes in each factor group) set REML to FALSE, because you can use maximum likelihood. If your random effects are crossed, don't set the REML argument because it defaults to TRUE anyway.
I have 2 random effects in my
lmer model. One is nested:
(1|Random1A/Random1B) + (1|Random2)
Should I set
TRUE (by default) or