Hi all,
I am doing an mixed regression analysis looking at protein intake and want to include sociodemographic factors such as gender and age into my model as fixed covariates.

I have coded males=0 and females =1, however when I run the analysis the model is including blank gender cells that have a dash in as another gender code!
I therefore am having 3 different options for gender.

Does anyone know how to fix this problem?

Thank you!