Solution

PERT Chart

Program Evaluation & Review Technique - Network diagram for uncertain durations. Uses optimistic (O), most likely (M), pessimistic (P) → $T_e = (O+4M+P)/6$. Nodes = events, arrows = activities. Finds critical path (longest). Probabilistic.

O—→A—→B—→ End  (with 3 estimates per arrow)

PERT vs Gantt

Aspect	PERT	Gantt
View	Network / dependencies	Bar chart / timeline
Duration type	Uncertain (3-point)	Fixed/deterministic
Shows dependencies	YES (critical path)	Weakly (bars)
Best for	Large R&D, high uncertainty, interdependent tasks	Small, stable, simple schedule
Complexity	High	Simple visual

When to use:

• PERT: Project manager faces high uncertainty / R&D (e.g., new software product), need to analyze risk and critical path.
• Gantt: Routine / Well-understood project, progress tracking for team, stakeholder presentation.

Often used together: PERT for planning, Gantt for monitoring.