You have probably heard the term burn-down and burn-up when referring to two different ways of tracking progress against some target in agile projects. but have you heard about the enhanced burn-down?
This old article goes over the burn-down and burn-up in detail. My take on this is that burn-downs are not that useful since it is hard to capture changes in scope. Burn-ups are better since changes in scope are clear. But at the same time I find it unsatisfactory to track against completion by looking at something that grows.
I prefer something that is often called the enhanced burn-down. Which is really a burn-up turned upside down with added trend lines since the assumption is that scope changes (or other discovered work) will happen at about the same rate throughout the project. The enhanced burn-down is described well here using a different term, but it is really the same thing.
So if you are still using burn-downs and burn-ups you should really take a closer look at the enhanced burn-down.