These are the slides from one of the IEEE EMC Distinguished Lectures I do. This reviews the most important process in engineering and what I think is the power of engineering and science: the process of "putting in the numbers." With this process we can confirm the root cause of an effect and distinguish when an explanation is correct and when it is wrong.  In this presentation we apply this process to look at 4 examples of important signal integrity statements and evaluate when they are true and when they are incorrect or a distraction. These topics relate to: the speed of a signal in a wire and the speed of the electrons, the impact of corners, the return current in a differential pair and the limits to FR4 for high speed serial links.