- Year not given
Activity versus event
Short answer
An activity is a work task that consumes time and resources, having duration. An event is a point in time marking start or completion, with zero duration and no resources. In AOA networks, activities are arrows and events are nodes.
What do you mean by activity? How is it different from an event?
An activity is a task or element of work performed during the project. It consumes time and resources, and has a duration. An event is a point in time that marks the start or completion of one or more activities; it consumes no time or resources.
| Basis | Activity | Event |
|---|---|---|
| Meaning | Work to be done | A point in time showing a status |
| Time | Consumes time (has duration) | Takes zero time (instant) |
| Resources | Needs resources and cost | No resources |
| Network representation | Arrow in AOA (activity on arrow); node in AON (activity on node) | Node/circle in AOA |
| Nature | Process | Accomplishment/milestone |
| Naming | Verb: "Design database" | Past tense: "Database designed" |
| Example | Writing code | Code completed |
| Emphasised in | CPM (activity-oriented) | PERT (event-oriented) |
(1) ---- Design database ----> (2)
event activity event
"Design (duration 5 days) "Design
started" complete"
Related terms
- Milestone: a significant event, with zero duration.
- Dummy activity: shows a dependency with no duration or resources (dashed arrow).
- Predecessor and successor: activities that must occur before or after.
Explanation
- In an AOA network, nodes represent events and arrows represent activities. Activity A from event 1 to event 2 starts when event 1 occurs, and when it finishes, event 2 occurs.
- Event 2 occurs only when all activities leading into it finish.
- In PERT, scheduling is event-oriented (events have earliest and latest expected times); in CPM, it is activity-oriented.
Example: "Install servers" is an activity taking 3 days. "Servers installed" is an event marking the milestone.
✓ Answer checked by Claude Opus 5.5 (high effort)
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