Activity Resource Estimating: Outputs

• Imposed dates on activity starts or finishes can be used to restrict the start or finish to occur either no earlier than a specified date or no later than a specified date. While several constraints are typically available in project management software, the “Start No Earlier Than” and the “Finish No Later Than” constraints are the most commonly used. Date constraints include such situations as agreed-upon contract dates, a market window on a technology project, weather restrictions on outdoor activities, government-mandated compliance with environmental remediation, and delivery of materiel from parties not represented in the project schedule. • The project sponsor, project customer, or other stakeholders often dictate key events or major milestones affecting the completion of certain deliverables by a specified date. Once scheduled, these dates become expected and can be moved only through approved changes. Milestones can also be used to indicate interfaces with work outside of the project. Such work is typically not in the project database and milestones with constraint dates can provide the appropriate schedule interface. .3 Activity List Described in Section 6.1.3.1. .4 Activity Attributes Described in Section 6.1.3.2. .5 Project Schedule Network Diagrams Described in Section 6.2.3.1. .6 Activity Resource Requirements Described in Section 6.3.3.1. .7 Resource Calendars Described in Sections 6.3.3.4. .8 Activity Duration Estimates Described in Section 6.4.3.1. .9 Project Management Plan The project management plan contains the schedule management plan, cost management plan, project scope management plan, and risk management plan. These plans guide the schedule development, as well as components that directly support the Schedule Development process. One such component is the risk register. • Risk Register. The risk register Sections 11.1 through 11.5 identifies the project risks and associated risk response plans that are needed to support the Schedule Development process. A Guide to the Project Management Body of Knowledge PMBOK ® Guide Third Edition 144 2004 Project Management Institute, Four Campus Boulevard, Newtown Square, PA 19073-3299 USA

6.5.2 Schedule Development: Tools and Techniques

.1 Schedule Network Analysis Schedule network analysis is a technique that generates the project schedule. It employs a schedule model and various analytical techniques, such as critical path method, critical chain method, what-if analysis, and resource leveling to calculate the early and late start and finish dates, and scheduled start and finish dates for the uncompleted portions of project schedule activities. If the schedule network diagram used in the model has any network loops or network open ends, then those loops and open ends are adjusted before one of the analytical techniques is applied. Some network paths may have points of path convergence or path divergence that can be identified and used in schedule compression analysis or other analyses. 6 .2 Critical Path Method The critical path method is a schedule network analysis technique that is performed using the schedule model. The critical path method calculates the theoretical early start and finish dates, and late start and finish dates, for all schedule activities without regard for any resource limitations, by performing a forward pass analysis and a backward pass analysis through the project schedule network paths. The resulting early and late start and finish dates are not necessarily the project schedule; rather, they indicate the time periods within which the schedule activity should be scheduled, given activity durations, logical relationships, leads, lags, and other known constraints. Calculated early start and finish dates, and late start and finish dates, may or may not be the same on any network path since total float, which provides schedule flexibility, may be positive, negative, or zero. On any network path, the schedule flexibility is measured by the positive difference between early and late dates, and is termed “total float.” Critical paths have either a zero or negative total float, and schedule activities on a critical path are called “critical activities.” Adjustments to activity durations, logical relationships, leads and lags, or other schedule constraints may be necessary to produce network paths with a zero or positive total float. Once the total float for a network path is zero or positive, then the free float — the amount of time that a schedule activity can be delayed without delaying the early start date of any immediate successor activity within the network path — can also be determined. .3 Schedule Compression Schedule compression shortens the project schedule without changing the project scope, to meet schedule constraints, imposed dates, or other schedule objectives. Schedule compression techniques include: • Crashing. Schedule compression technique in which cost and schedule tradeoffs are analyzed to determine how to obtain the greatest amount of compression for the least incremental cost. Crashing does not always produce a viable alternative and can result in increased cost. A Guide to the Project Management Body of Knowledge PMBOK ® Guide Third Edition 2004 Project Management Institute, Four Campus Boulevard, Newtown Square, PA 19073-3299 USA 145