if ethnicity in r would be a fixed variable what kind of models does ethnicity use can ethnicity be a mixed model how to model ethnicity how is ethnicity modeled is ethnicity a fixed variable in r why is ethnicity a variable in r why is ethnicity a variable in random sampling in r how many observations in r can you model the effect of ethnicity why does ethnicity affect blood pressure how to predict multilevel r effects can ethnicity be a fixed or random covariate is ethnicity the same as a fixed covariate which is a fixed covariate of ethnicity can the variable ethnicity be a multiple covariate is bp variable a random covariate can an ethnicity be a variable in t r models when should sex be modeled as a variable in mixed model what kind of correlation is the ethnicity in r