PERT

PERT

Definition & Basic Concepts

  • PERT stands for Programme Evaluation and Review Technique.
  • It is a project management tool used to schedule, organise and coordinate tasks involved in a project.
  • PERT involves identifying the time required to complete each task and the dependencies between tasks.

Characteristics of PERT

  • PERT uses a network diagram which represents each task in a project as a node, with arrows depicting the sequence and dependencies between tasks.
  • This technique identifies critical and non-critical tasks. Critical tasks are tasks that must be completed on time for the project to meet its deadline.
  • PERT also calculates the earliest start time, earliest finish time, latest start time and latest finish time for each task.

Computation in PERT

  • The estimation of task durations in PERT is often done using a triple estimation approach - optimistic time, pessimistic time, and most likely time.
  • The expected time of each activity is calculated using the formula (Optimistic Time + 4*Most Likely Time + Pessimistic Time)/6.
  • The calculation of Earliest Start Time (EST) and Earliest Finish Time (EFT) is done by moving from the start node to the end node of the PERT network. EST is carried through each activity, while EFT is calculated as EFT = EST + Task Time.
  • Conversely, Latest Start Time (LST) and Latest Finish Time (LFT) calculations are done by moving from the end node to the start node. LFT is carried through each activity, while LFT is calculated as LST = LFT - Task Time.

General Steps in PERT

  • The process of creating a PERT chart generally includes: identifying tasks and milestones, determining the sequence of tasks, constructing a network diagram, estimating time for each task, identifying the critical path, and updating the PERT chart as the project progresses.

Advantages & Limitations

  • Advantages of PERT include its ability to handle complex and interdependent tasks, adjust schedules and predict project completion times.
  • Limitations of PERT are that it assumes a fixed time estimate for each task, which isn’t always accurate, and that it represents tasks as a single event rather than a process.

Applications

  • PERT is commonly used in major projects including research and development projects, construction projects, and even the planning of large events.