Critical Path Method (CPM) vs. Program Evaluation Review Technique (PERT)

Critical Path Method (CPM) vs. PERT

HL (time to completion may be delayed without affecting the beginning of another and final term), HM (the worst case of free float.) Critical path: the path of longer duration and is defined by the sequence of activities that mark critical events in the network. These activities are styled with a double arrow. An activity is critical when it has no slack time, and an event is critical when its TE (earliest time) and TL (latest time) are equal. We must pay critical attention to these routes, as any delay may affect the entire project. Beginning and ending events are critical.

PERT (Program Evaluation Review Technique): It is a probabilistic system that assigns each possible activity three durations: pessimistic, optimistic, and most likely, using the following formula: D = (a + 4m + b) / 6. For the computation of time, this formula is used. However, it is important to know that there is a likelihood that a project does not exceed the time allotted for execution. For this, we use the independence probability factor: Z = (Ts - Te) / Ω(Te) (where Ts is the target stage, Te is the earliest stage, and Ω is the critical path variance). The work will be feasible if we have a 25% chance and will have minimal statistical certainty from 97% probability.

CPM (Critical Path Method): A method of planning and scheduling represented by a network of arrows based on the establishment of the critical path. It is a deterministic method that is developed on the basis that each activity is given a fixed term depending on available resources, experience, or performance. The CPM establishes two time limits: the maximum and minimum that an activity can last. Time influences the corresponding costs of the activity and the time of the final event. Details of departure: every activity is assigned a duration depending on experience, means of duration estimates, and resources. Time to act and events is the time in which to develop an activity. These times are TMPC, TMPT, TMTC, TMTT. Time of an event: each event is assigned two times: TE (earliest), TL (latest). Clearance of an event: the time difference between the latest and earliest time of an event. Slack act: the difference between the maximum time to perform an activity and the time required for the execution of the same - HT (may be delayed while conducting an activity without affecting the completion date).