# ATAM Phase 1: Architecture-centric Analysis

**In short:** Phase 1 of ATAM opens an architecture evaluation. The evaluation team, the architects and other participants start by learning how the method works. Phase 2 then widens the input to a larger stakeholder group.

## Explanation

ATAM is the Architecture Tradeoff Analysis Method, from the Software Engineering Institute. It evaluates an architecture against quality goals. See the article "Architecture Tradeoff Analysis Method (ATAM)" for the full picture.

An evaluation usually takes three to four days in total. It brings together a trained evaluation team, the architects and representatives of the architecture's stakeholders. A stakeholder is anyone with an interest in the system.

The method runs in two phases. Phase 1 is the architecture-centric part. It starts with step 1: the evaluation leader describes the evaluation method to everyone present. That way all participants know how the evaluation will run before the analysis starts.

Phase 2 covers steps 7 to 9 and finishes the evaluation. It widens the input to the larger stakeholder group. That group brainstorms scenarios, the results are re-analyzed, and the results are presented.

The purpose of the whole method is to help choose a suitable architecture. It does this by finding trade-offs and sensitivity points. A trade-off is a decision where improving one quality worsens another. See "Trade-off Point" and "Sensitivity Point".

## Example

A team plans to evaluate the architecture of an order system. At the start, the evaluation leader meets the evaluation team and the architects. The leader explains how the evaluation will proceed. Only after this shared start does the work move on. Later, a wider stakeholder group joins to finish the evaluation.

## Trade-offs

The facts available here describe only step 1 of Phase 1 and its link to Phase 2. They do not cover the other Phase 1 steps, the inputs and outputs, or the preparation effort. Read "ATAM Phase 1 and 2 Activities" for more on those.



## Checks

- The evaluation plan states that the evaluation leader describes the evaluation method to all participants at the start.
- The participants include a trained evaluation team, the architects and stakeholder representatives.
- The plan allows for about three to four days in total for the evaluation.

## Related

- [Architecture Tradeoff Analysis Method (ATAM)](https://arc.fuet.ch/concepts/evaluation/architecture-tradeoff-analysis-method-atam.md)
- [ATAM Phase 1 and 2 Activities](https://arc.fuet.ch/concepts/evaluation/atam-phase-1-and-2-activities.md)
- [ATAM Application Phases](https://arc.fuet.ch/concepts/evaluation/atam-application-phases.md)
- [ATAM Roles](https://arc.fuet.ch/concepts/evaluation/atam-roles.md)
- [Sensitivity Point](https://arc.fuet.ch/concepts/evaluation/sensitivity-point.md)
- [Trade-off Point](https://arc.fuet.ch/concepts/evaluation/trade-off-point.md)
- [Software Architecture Evaluation](https://arc.fuet.ch/concepts/evaluation/software-architecture-evaluation.md)
- [ATAM Evaluation Team and Stakeholder Selection](https://arc.fuet.ch/concepts/evaluation/atam-evaluation-team-and-stakeholder-selection.md)

## Sources

- [Architecture Tradeoff Analysis Method® Collection | CMU Software Engineering Institute](https://www.sei.cmu.edu/library/architecture-tradeoff-analysis-method-collection/) — sei.cmu.edu, accessed 2026-11-09
- [Architecture tradeoff analysis method - Wikipedia](https://en.wikipedia.org/wiki/Architecture_tradeoff_analysis_method) — en.wikipedia.org, accessed 2026-11-09