> m1 <- clm(categorical_FOD_FODs ~ 0 + Condition_FODs:Language_used_FODs - 1, data = indvar_FODs) Error: response in 'formula' needs to be a factor please define the factors
levels(indvar_FODs$Condition_FODs) levels(indvar_FODs$Language_used_FODs) levels(indvar_FODs$categorical_FOD_FODs)