The program evaluation and review technique (PERT) shows relationships between defined tasks in a project without taking into consideration a time line. This chart is an excellent way to identify dependencies of tasks based on other tasks.
This chart allows project managers to identify the critical path of a project to minimize any time delays to the project. According to Craig Borysowich in his article “Pros & Cons of the PERT/CPM Method stated the following advantages and disadvantages:
“PERT/CPM has the following advantages:
A PERT/CPM chart explicitly defines and makes visible dependencies (precedence relationships) between the WBS elements,
PERT/CPM facilitates identification of the critical path and makes this visible,
PERT/CPM facilitates identification of early start, late start, and slack for each activity,
PERT/CPM provides for potentially reduced project duration due to better understanding of dependencies leading to improved overlapping of activities and tasks where feasible.
PERT/CPM has the following disadvantages:
There can be potentially hundreds or thousands of activities and individual dependency relationships,
The network charts tend to be large and unwieldy requiring several pages to print and requiring special size paper,
The lack of a timeframe on most PERT/CPM charts makes it harder to show status although colors can help (e.g., specific color for completed nodes),
When the PERT/CPM charts become unwieldy, they are no longer used to manage the project.” (Borysowich, 2008)
Traditionally PERT charts are used in the initial planning of a project like in a project that is utilizing the waterfall approach. Once the chart was created then project managers could further analyze this data to determine the earliest start time for each stage in the project. This is important because this information can be used to help forecast resource needs during a project and where in the project.
However, the agile environment can approach this differently because of their constant need to be in contact with the client and the other stakeholders. The PERT chart can also be used during project iteration to determine what is to be worked on next, such as a prioritized To-Do list a wife would give her husband at the start of a weekend.
In my personal opinion, the COTS-centric environment would not really change how a company uses a PERT chart in their day to day work. The only thing I can is that there would be less tasks to include in the chart because the functionally milestones are already completed when the components are purchased.
References:
http://www.netmba.com/operations/project/pert/
http://web2.concordia.ca/Quality/tools/20pertchart.pdf
http://it.toolbox.com/blogs/enterprise-solutions/pros-cons-of-the-pertcpm-method-22221
