Architecture Trade-Off Analysis Method

According to SEI, The main part of the ATAM consists of nine steps separated into four groups:

1. Presentation, which involves exchanging ideas through presentations
2. Investigation and analysis, which involves assessing key quality attribute requirements vis-a-vis architectural approaches
3. Testing, which involves checking the results to date against the needs of all relevant stakeholders
4. Reporting, which involves presenting the end results
   

http://www.sei.cmu.edu/publications/documents/00.reports/00tr004.html