GLOSSARY

Activity   The work or effort needed to achieve a result. It consumes time and usually consumes resources.

Activity Description   A statement specifying what must be done to achieve a desired result.

Activity-on-Arrow   A network diagram showing sequence of activities, in which each activity is represented by an arrow, with a circle representing a node or event at each end.

Activity-on-Node   A network diagram showing sequence of activities, in which each activity is represented by a box or circle (that is, a node) and these are interconnected with arrows to show precedence of work.

Authority   The legitimate power given to a person in an organization to use resources to reach an objective and to exercise discipline.

Backward-Pass Calculation   Calculations made working backward through a network from the latest event to the beginning event to calculate event late times. A forward-pass calculation determines early times.

Calendars   The arrangement of normal working days, together with nonworking days, such as holidays and vacations, as well as special work days (overtime periods) used to determine dates on which project work will be completed.

Change Order   A document that authorizes a change in some aspect of a project.

Control   The practice of monitoring progress against a plan so that corrective steps can be taken when a deviation from plan occurs.

CPM   An acronym for critical path method. A network diagramming method that shows the longest series of activities in a project, thereby determining the earliest completion for the project.

Crashing   An attempt to reduce activity or total project duration, usually by adding resources.

Critical Path   The longest sequential path of activities that are absolutely essential for completion of the project.

Dependency   The next task or group of tasks cannot begin until preceding work has been completed, thus the word dependent or dependency.

Deviation   Any variation from planned performance. The deviation can be in terms of schedule, cost, performance, or scope of work. Deviation analysis is the heart of exercising project control.

Dummy Activity   A zero-duration element in a network showing a logic linkage. A dummy does not consume time or resources but simply indicates precedence.

Duration   The time it takes to complete an activity.

Earliest Finish   The earliest time that an activity can be completed.

Earliest Start   The earliest time that an activity can be started.

Estimate   A forecast or guess about how long an activity will take, how many resources might be required, or how much it will cost.

Event   A point in time. An event is binary. It is either achieved or not, whereas an activity can be partially complete. An event can be the start or finish of an activity.

Feedback   Information derived from observation of project activities that is used to analyze the status of the job and take corrective action if necessary.

Float   A measure of how much an activity can be delayed before it begins to impact the project finish date.

Forward-Pass Method   The method used to calculate the earliest start time for each activity in a network diagram.

Free Float   The amount of time that an activity can be delayed without affecting succeeding activities.

Gantt Chart   A bar chart that indicates the time required to complete each activity in a project. It is named for Henry L. Gantt, who first developed a complete notational system for displaying progress with bar charts.

Hammock Activity   A single activity that actually represents a group of activities. It “hangs” between two events and is used to report progress on the composite it represents.

Histogram   A vertical bar chart showing (usually) resource allocation levels over time in a project.

i-j Notation   A system of numbering nodes in an activity-on-arrow network. The i-node is always the beginning of an activity, while the j-node is always the finish.

Inexcusable Delays   Project delays that are attributable to negligence on the part of the contractor, which lead in many cases to penalty payments.

Latest Finish   The latest time that an activity can be finished without extending the end date for a project.

Latest Start   The latest time that an activity can start without extending the end date for a project.

Learning Curve   The time it takes humans to learn an activity well enough to achieve optimum performance can be displayed by curves, which must be factored into estimates of activity durations in order to achieve planned completion dates.

Leveling   An attempt to smooth the use of resources, whether people, materials, or equipment, to avoid large peaks and valleys in their usage.

Life Cycle   The phases that a project goes through from concept through completion. The nature of the project changes during each phase.

Matrix Organization   A method of drawing people from functional departments within an organization for assignment to a project team, but without removing them from their physical location. The project manager in such a structure is said to have dotted-line authority over team members.

Milestone   An event of special importance, usually representing the completion of a major phase of project work. Reviews are often scheduled at milestones.

Most Likely Time   The most realistic time estimate for completing an activity under normal conditions.

Negative Float or Slack   A condition in a network in which the earliest time for an event is actually later than its latest time. This happens when the project has a constrained end date that is earlier than can be achieved, or when an activity uses up its float and is still delayed.

Node   A point in a network connected to other points by one or more arrows. In activity-on-arrow notation, the node contains at least one event. In activity-on-node notation, the node represents an activity, and the arrows show the sequence in which they must be performed.

PERT   An acronym for program evaluation and review technique. PERT makes use of network diagrams as does CPM, but in addition applies statistics to activities to try to estimate the probabilities of completion of project work.

Pessimistic Time   Roughly speaking, this is the worst-case time to complete an activity. The term has a more precise meaning that is defined in the PERT literature.

Phase   A major component or segment of a project.

Precedence Diagram   An activity-on-node diagram.

Queue   Waiting time.

Resource Allocation   The assignment of people, equipment, facilities, or materials to a project. Unless adequate resources are provided, project work cannot be completed on schedule, and resource allocation is a significant component of project scheduling.

Resource Pool   A group of people who can generally do the same work so that they can be chosen randomly for assignment to a project.

Risk   The possibility that something can go wrong and interfere with the completion of project work.

Scope   The magnitude of work that must be done to complete a project.

Statement of Work   A description of work to be performed.

Subproject   A small project within a larger one.

Time Now   The current calendar date from which a network analysis, report, or update is being made.

Time Standard   The time allowed for the completion of a task.

Variance   Any deviation of project work from what was planned. Variance can affect costs, time, performance, or project scope.

Work Breakdown Structure   A method of subdividing work into smaller and smaller increments to permit accurate estimates of durations, resource requirements, and costs.