-1-PERT was developed primarily to simplify the planning and scheduling of large and complex projects-3-First developed by the United States Navy in 1950s.-4-Event-oriented Technique rather than start- and completion-oriented.
The critical path method (CPM) is an algorithm for scheduling a set of project activities.
-1-Identify the specific activities and milestones.-2-Determine the proper sequence of the activities.-3-Construct a network diagram.-4-Estimate the time required for each activity.-5-Determine the critical path.-6-Update the PERT chart as the project progresses.
-1-The activities are the tasks required to complete a project.-2-The milestones are the events marking the beginning and the end of one or more activities.-3-It is helpful to list the tasks in a table that in later steps can be expanded to include information on sequence and duration.
-1-Weeks are a commonly used unit of time for activity completion, any consistent unit of time can be used.-3-2-So that there is a approximately a 1% chance that the activity will be completed within the optimistic time.-4-Note that this time is different from the expected time.
The implication being thatthe expected time is the average time the task would require if the task were repeated on a number of occasions over an extended period of time.
-1-A work breakdown structure element may be a product, data, a service, or any combination-4-Better understanding of dependencies leading to improved overlapping of activities and tasks were feasible.
Program Evaluation and Review Technique (PERT)
Presented By:Abhishek Pachisia B.Tech IT 090102801
Program Evaluation and Review Technique. Analyze the tasks. United States Navy. Event-oriented Technique Major Factor – Time Ex: 1968 Winter Olympics in Grenoble
The main objective of PERT : To facilitate decision making and To reduce both the time and cost required to complete a project. Related Tools: Critical Path Method. Gantt chart Applied to: Very large-scale, One-time, Complex, Non-routine infrastructure and Research and Development projects
Specific activities and milestones. Sequence of the activities. Network diagram. Estimate the time. Critical path. Update the PERT chart.
Activities. Milestones. It is helpful to list the tasks in a table.
May be combined with the activity identification step Since the activity sequence is evident for some tasks. Other tasks may require more analysis To determine the exact order in which they must be performed.
Activity sequence information A network diagram can be drawn showing the sequence of the serial and parallel activities. Each activity represents: A node in the network, The arrows represent: The relation between activities. Software packages simplify this task By automatically converting tabular activity information into a network diagram.
Weeks are a commonly used unit of time for activity completion. A distinguishing feature of PERT. Its ability to deal with uncertainty in activity completion time. Optimistic time(O) The shortest time in which the activity can be completed. To specify optimistic time to be three standards deviations from the mean. Most likely time(M) The completion time having the highest probability.
Pessimistic time (P) the maximum possible time required to accomplish a task, assuming everything goes wrong (but excluding major catastrophes). PERT assumes a beta probability distribution for the time estimates. Estimated Time(TE) The best estimate of the time required to accomplish a task, accounting for the fact that things dont always proceed as normal. TE = (O + 4M + P) ÷ 6
The critical path is Determined by adding the times for the activities in each sequence. Determining the longest path in the project. The critical path determines the total calendar time required for the project. If activities outside the critical path speed up or slow down (within limits), the total project time does not change. The amount of time that a non – critical path activity can be delayed without the project is referred to as a slack time.
Critical Path is helpful to determine ES – Earliest Start time EF - Earliest Finish time LS – Latest Start time LF - Latest Finish time The variance in the project completion time can be calculated by summing the variances in the completion times of the activities in the critical path. The project can be accelerated by adding the resources required to decrease the time for the activities in the critical path. Shortening of the project sometimes is referred to as Project Crashing.
Make adjustments in the PERT chart as the project progresses. As the project unfolds, the estimated times can be replaced with actual times. In cases where There are delays, Additional resources may be needed to stay on schedule The PERT chart may be modified to reflect the new situation.
Explicitly defines and makes visible dependencies between the WBS elements Facilitates identification of the critical path. Facilitates identification of Start date, End date, and Slack time for each activity, Provides potentially reduced project duration. The large amount of project data can be organized & presented in diagram for use in decision making.
Hundreds or thousands of activities and individual dependency relationships Not easily scalable for smaller projects The network charts tend to be large and unwieldy requiring several pages to print. The lack of a timeframe on most charts makes it harder to show status although colours can help When the charts become unwieldy, they are no longer used to manage the project.
In this Case Study, the Project manager knows The succession of the project activities , Optimistic Time, Pessimistic Time and Most Likely Time All the times known are in weeks.
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