So I'm trying to run a mixed-effects model looking at the relative intensity of Arabic and English fricatives produced by bilingual Arabic-English speakers; for context, I'm looking at /f/ and /v/, Arabic doesn't have /v/ natively so any instances of its production were in English.
I tried to run this model:
lmer(intensity_relative ~ segment * position + position * language + segment * language + (1|speaker), data = df3_uae)
However, I get the warning: fixed-effect model matrix is rank deficient so dropping 1 column/coefficient and the model doesn't show any interaction results for segment * language. Could this be because in the language column "Arabic", there isn't any recorded instance of /v/ so there's a missing segment? If not, is there a way to fix this?