|Tip 11||Estimates Need Accuracy, Not Precision|
Each of these techniques so far stress accuracy of the estimate by showing how imprecise the estimate is. Early in the project, it’s impossible to know what date the project will release—unless the project team is free to define what they will release and how good it is.
Precision is the exactness of the measurement, the number of decimal places. Accuracy is how close you are to the estimate. What you care about for scheduling is accuracy—how close your prediction of the task durations or schedule is, not which hour of the day a task will complete or the project will end.
Don’t be worried about how precise your estimate is; be more worried about how accurate it is.