What actually changes between a Class 5 and a Class 3 estimate
Maturity of definition, not effort, separates the classes. What moves between Class 5 and Class 3, what must not, and the two questions that expose the real class.
A Class 5 estimate is a screening tool, not a budget
Minus 50 to plus 100 percent is not a failure of the estimator. It is what concept-stage information supports, and it has a job to do.