A number of expressions and acronyms commonly occur in any basic discussion of Project Management. Most refer to techniques used in formal project planning and evaluation. There follows a brief description of each.
- A. Network analysis
- B. Critical path method
- C. PERT (Programme Evaluation Review Technique)
- D. Gantt charts
A. Network analysis
Network analysis is a method of task scheduling within a project, whereby task dependencies can be identified. A task network can then be built up and time tolerances identified. Figure 8.2 shows part of a network analysis diagram, where each circle represents a distinct task.
Network analysis is in fact a collective term for two different approaches to project planning: Critical Path Method and PERT.
Figure 8.2. Network analysis diagram. Each circle represents a discrete task, with lines showing dependencies. (Source: McGraw-Hill)
B. Critical path method
Critical Path Method (CPM), is a procedure for using network analysis to identify those tasks which are on the critical path: ie where any delay in the completion of these tasks will lengthen the project timescale, unless action is taken. For all tasks off the critical path, a degree of tolerance is possible (eg late start, late completion, early start, etc.). Network charts and CPM analysis used to be carried out by hand. Software is now available which requires the user only to enter the tasks, duration of each task and dependencies upon other tasks; a network chart and CPM is then automatically created.
C. PERT (Programme Evaluation Review Technique)
PERT was developed in 1958 by the US Navy to meet the requirements of project planning in conditions of substantial uncertainty – where the number of tasks and sub-contractors render traditional techniques unworkable. The system relies fundamentally upon probabilistic techniques, and is not really relevant to the present context.
D. Gantt charts
The Gantt chart (Figure 8.3) is a basic means of presenting visually a project programme. Essentially a bar chart, it is a useful aide memoire of where the project stands, but is only in fact a static representation of a dynamic situation. In particular, interdependencies between one task and another (each represented by a distinct bar) are not shown, and must remain in the mind of whoever draws up or uses the chart.
Figure 8.3. High level Gantt chart. Eadch bar constitutes an aggregate of numerous sub-tasks, which will be continued in their own Gantt chart. A hierarchy of Gantt charts can therefore be built up.
Nevertheless the Gantt chart is often used as the benchmark by which a project’s progress is measured and is commonly circulated to all team leaders. Most Project Management software packages will offer the option to produce a Gantt chart.