“Medicine is a social science”, this has been the mantra of public health since 1848. Today, medicine is a computational social science. In this talk, I'll give an overview of the Global Burden of Disease Study (GBD), and describe some of its many algorithmic challenges. GBD is a systematic effort to produce estimates of how 200+ diseases, injuries, and risk factors impact people around the world. Naturally, there are a lot of numbers to crunch. But you may be surprised to learn how many of the relevant numbers are missing. And the numbers we do have often don't add up. This is where we need computational tools, and where we leverage research from probability theory and machine learning, as well as economics and political science. I'll give you a quick tour of the interdisciplinary area that is Health Metrics.