Undergrad math course vs semi-related grad course

[bcarmel]

I am applying for biostatistics grad school for Fall 2019. Given that I will have taken three math classes (multi, intro prob and stats, and lin alg) in college by the time I turn in applications given my current plans, would it be more beneficial for me to take another undergrad math course(ODE, real analysis, or mathematics of data science) next semester, or continue with my plan of two grad-level courses next semester? The grad class I would drop in favor of a math class would be Computational Structural Biology (i.e. protein modeling).

[Bayesian1701]

Real Analysis for sure if you are going for a PhD or a top masters.  Even you already have a semester or real analysis, real analysis would be better.  You don't need a biology background for biostats, but you need a math background.  If all you have are the basic prereqs (calculus, a stats course, linear algebra), you are going to be at a disadvantage to math majors with 10+ math courses.  It is important to note that most Ph.D. applications will be due in December and January so you might not have fall grades, but even taking real analysis and having an in progress on your transcript will help you.  For Masters applications you might have more time to include grades.