On large software development and acquisition programs, testing phases typically extend over many months. It is important to forecast the quality of the software at that future time when the schedule calls for testing to be complete. In this article, originally published in CrossTalk, Paul Below shows how Walter Shewhart’s Control Charts can be applied to this purpose, in order to detect a signal that indicates a significant change in the state of the software. This signal detection is then used to improve mapping of project progress to forecast curves and thereby improve estimates of project schedule.