PERT (Program Evaluation and Review Technique) chart

Basic idea

Network diagram for project scheduling with probabilistic durations. Each activity has ES/LS/EF/LF/slack; the longest path is the critical path — delays there delay the project. “Crashing” shortens the critical path.

Key formulas

• $T_E = (O + 4M + P)/6$
• $\sigma = (P - O)/6$
• $\text{Slack} = LS - ES = LF - EF$
• Critical path: total slack = 0

PERT (Program Evaluation and Review Technique) chart

PERT charts help

• Understand the characteristics of the project that will let project managers do scheduling trade-offs
• Perform critical path analysis
• Monitor project progress and re-plan

PERT charts

Involves calculating the following estimates

• Earliest start time (ES)
• Latest start time (LS)
• Earliest finish time (EF)
• Latest finish time (LF)
• Slack time

Critical path

• Path with longest duration
• Activities on the critical path have a total free slack of zero
• A delay in any of the activities in the critical path will cause the project to delay

Crashing the critical path

• Shortening the total duration of the project by shortening the critical path by
  • Removing dependencies between activities in the critical path
  • Shortening the duration of activities in the critical path

Siblings

• Definitions
• Developing Project Schedule
• Earned Value Analysis (EVA)
• Effort-time estimation
• Milestones vs Deliverables
• Planning in Agile
• Project Schedule
• Project Scheduling
• Project Tracking and Control
• Tasks