> mod <- glmer('categorical_FOD_FODs ~ Condition_FODs + Language_used_FODs + (1 | subject_FODs)', + data = indvar_FODs, family = binomial) boundary (singular) fit: see help('isSingular') edit the code due to 'isSingular'

m2 <- glmer('FOD_categorical ~ Condition + Language_used + (1 | subject)', 
+              data = indvar, family = binomial)
fit <- lmer('FOD_categorical ~ Condition + Language_used + (1 | subject)', 
+              data = indvar)