One of the most important jobs of a project manager is to manage a projects budget and schedule. These tasks can easily be very difficult to accomplish on projects that are complex, especially since successful project execution relies heavily on people who are expected to perform their roles individually and as a team. One of the most difficult aspects of managing projects is estimating how fast and effectively humans will perform a task; that is, determining how productive workers collectively will be each day, each week, or within any time period during the life of a project. Because...