A basic grasp of statistics is an essential skill for any evaluator. Khulisa feels CrashCourse is a great YouTube resource for introductory courses, from sociology to computer science. In this series of videos Adriene Hill demystifies statistics, highlighting how it can shape government policy or misinform the public when used incorrectly.
The CrashCourse channel has close to 10million subscribers and includes useful sidenotes and comments on the topic covered.