A Mental Model & Framework You Can Use For New Products, Existing Products, and Even PM Interviews — In this series… Part 1: WTF is a Metric? — introduction to the basics of metrics, what it is, and why it matters. Part 2: 4 Steps to Defining GREAT Metrics for ANY Product — how to develop a metric from scratch. Part 3: WTF is Your Metric Doing to Your Customers? —…