This article is an expanded version of the math part of an article I cowrote with marine biologist Dr. Andrew Rhyne about how many well-meaning public health professionals have misinterpreted the math behind test efficiency, Bayes’ Theorem. This misinterpretation has lead to dangerous public policy positions. Anyone with a math allergy is invited to read that article instead. I and Dr. Andrew Rhyne, marine biologist and my longtime collaborator in fighting wildlife crime, have spent a lot of time in the last several months working on how best to fight the COVID-19 pandemic, especially in college communities like our own Roger Williams University.