Targets, progress and status
PERT / project dependency network
Shows project dependencies and durations to support schedule-path analysis.
- Diagram
- Schedule
- Dependency
What it answers
Which tasks constrain the project schedule?
- Shape
- Task nodes linked by precedence arrows
- What it shows
- Critical paths and slack under the model.
Example
The question
Which tasks decide when the store fit-out can finish?
Store fit-out tasks and dependencies, durations in days (PERT network)
Illustrative data. It belongs to no company.
When to use it
Use it when
Dependency-based schedule analysis with explicit assumptions.
Avoid it when
Cycles, unmodelled resource constraints or uncertain durations treated as guaranteed.
How to read it
Follow dependencies and sum durations along valid paths.
Note
Uncertain durations can use optimistic, likely and pessimistic estimates.
The data you need
- Layout
- Task table plus dependency table
- Fields
- Tasks: TaskID,Duration; Links: PredecessorID,SuccessorID
- One row is
- One task duration or one precedence relationship. What is the grain?
- Rules
- Use an acyclic dependency graph and consistent duration units. Define dependency types and lags.
- Optional
- Optimistic,MostLikely,Pessimistic durations for PERT estimates; standard expected duration is (O+4M+P)/6.
- Preparation
- Validate an acyclic dependency graph, durations and lags; calculate path totals and any PERT expected durations.
- Units
- Durations and lags share a unit. Path totals assume the stated dependency and resource model.
Worked example
A3 days->B5 days->C2 days gives 10 days in sequence with no lags. Parallel branches would require comparing path totals.
| Tasks: TaskID | Duration |
|---|---|
| A | 3 |
| B | 5 |
| C | 2 |
| Links: PredecessorID | SuccessorID |
| A | B |
| B | C |