DEFINING AND SEQUENCING PROJECT TASKS

Developing a realistic and useful project schedule is a critical part of project planning. The project team must define and sequence project tasks, estimate their durations and resource requirements, and decide how to communicate schedule information.

A task or activity is an element of work, normally found on the WBS, that has an expected duration, a cost, and resource requirements. In order to estimate duration and resources required for a task, the project team must first clearly define tasks by developing a more detailed WBS and supporting explanations.

A dependency or relationship shows the sequencing of project tasks. There are three basic types of dependencies:

- Mandatory dependencies are inherent in the nature of the work. For example, you cannot test code until after it is written.

- Discretionary dependencies are defined by the project team. For example, a project team might decide not to start a detailed design of a new system until users sign off on the analysis work.

- External dependencies involve relationships between project and nonproject tasks. For example, the installation of a new operation system and other software may depend on delivery of new hardware from an external supplier.

Project network diagrams display the sequencing of tasks. Most project management software displays project network diagrams using the precedence diagramming method where boxes represent tasks and arrows connect related tasks.

The longest path through a project network diagram is called the critical path. The length of the critical path is the minimum amount of time required to complete a project.If any task on the critical path takes longer than planned, the project completion date will be extended.

Take time to define project tasks and dependencies clearly. Task definitions and dependencies provide the basis for time, cost, and resource estimates. Use project network diagrams to display task sequencing and determine the critical path.