III.C.2 Project planning and estimation tools
Excerpt From The Certified Manager of Quality/Organizational Excellence Handbook
Work Breakdown Structure. Except, perhaps, for extremely small, short-duration projects, a work breakdown structure (WBS) is created by the project team. If any pertinent organizational groups are not represented on the project team, such groups should be consulted before committing them to work responsibilities on the WBS.
Typical terms for the descending levels of a WBS are project level, subproject level, work unit/component level (optional), work package level, and task level (may be optional). Usually, cost accumulation reaches down to the work package level. Figure 10.4 shows a three-level WBS under development (project level, subproject level, and work package level only). The task level has not yet been added, nor have the identification numbers for each box (usually a decimal hierarchy to aid accounting in building costs from the lowest to the highest level), the name of the person or function responsible, nor time and cost estimates.
The WBS is the focal point for planning. It provides the structure of the project and the basis for estimating time and costs. The WBS also enables the project team to visually see the relationships of all parts to the whole: the deployment of tasks and responsibilities, and the accounting structure by which costs will be accumulated and measured against budget.
Note: A WBS may be created in outline format, the line indentations indicating the levels of the structure. Advantages of the outline format are that the outline is easy to compile (word processing) and easy to modify. A disadvantage is the difficulty in clearly seeing the overall view of the project and its interfaces. The input to some project management computer programs that compile the WBS and other documents is similar to the outline format.
Gantt Chart. After the WBS has been created, the tasks or steps are time-phased on a Gantt chart. Gantt charts may be created at any level of detail needed for managing the project, although not generally at the work unit level. Figure 10.6 shows a partial Gantt chart at a work package level. As project planning progresses, the chart can be amended to display milestones (critical points for measurement), and as work progresses bars added representing actual times elapsed, and other symbols to indicate project status.
Activity Network Diagram. An activity network diagram (AND) is a simple chart showing the dependencies of each task on other tasks in the project (what has to precede a given task and what has to follow). This chart is used in understanding and communicating task relationships within the project.
Critical Path Method. A critical path method (CPM) chart is an expanded AND showing a time estimate for each activity. The sequence of interrelated activities that takes the longest is the critical path. CPM charts are commonly used for projects where there are prior data or experience in documenting reasonably accurate time estimates. Computer software is usually employed for more complex projects. The critical path is the series of steps taking the longest time. No slack time exists on the critical path.
Quality Management BOK Reference
III Management Elements and Methods
III.C Project Management
III.C.2 Project planning and estimation tools - Use tools such as risk assessment, benefit-cost analysis, critical path method (CPM), Gantt chart, PERT, and work breakdown structure (WBS) to plan projects and estimate related costs.
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