Online Ph.d. In Public Health: The Advantage - The biggest advantage of an online Ph.D. in Public Health is you can study at your own time and pace. You can enroll for a Public Health Ph.D. course anytime, which mean you do not have to start at the beginning of the fall or spring semesters for an online Public Health Ph.D. program. This is the major reason many people prefer to get their Ph.D. in Public Health online.