A PERT chart is a project management method that allows to get a visual representation of a project workschedule which is used to coordinate and organize the activities of a project.
PERT Program Evaluation Review Technique was developed by the US Navy in the late 1950’ s for Ballistic Missile Program in order to find a simple system to manage and organize complex objectives and thousands of contractors.
PERT Program Evaluation Review Technique
In pert method, three estimate techniques are used to determine the activity durations which are below;
• Most Likely Estimate
• Optimistic Estimate
• Pessimistic Estimate
Most Likely Estimate (Tm)
The most likely estimate is an estimate of the most probable duration of a particular activity.
Optimistic Estimate (To)
The Optimistic estimate is an estimate of the shortest duration of activity that takes into consideration the known parameters that can effect performance.
Pessimistic Estimate (Tp)
The Pessimistic estimate is an estimate of the longest duration of activity that takes into consideration the all un-favorable conditions that can effect performance.
The Pert Formula
The formula to calculate the PERT is as follows:
PERT Estimate = (To + 4Tm + Tp)/6
Standard Deviation = (Tp – To)/6
Benefits of PERT
The Pert Method has many benefits such as:
– It enables to define and visualize dependencies between the activities in the network diagram.
– It enables to determine the critical path of the workschedule.
– It enables to accelerate projects by the help of efficient planning of activities.
– It improves the quality of planning for decision making.
Limitations of PERT
Following are the few limitations of PERT Method:
– It is less effective for smaller projects
– It is a complicated method which makes hard to analyze the results.
– It is a time and cost consuming method because of its complexity
– Inputs must be unbiased and accurate because this method depends on these estimates and inputs. Otherwise workschedule will be effected and incorrect results will occur.
The Pert Method is a powerful tool for implementing “what if” scenarios and is practical in planning for possible obstacles. But it is not very easy to use. Employing softwares enable to make PERT calculations easier and fastly.