A decision matrix is a visual comparison of how various alternatives stack up against one another. Use a decision matrix to qualify design alternatives so a decision can be made. A decision matrix can also be used in documentation as a part of the design’s rationale.

Benefits

• Use to compare a variety of decisions such as patterns, technologies, or frameworks.

• Visualize relative strengths and weaknesses among decisions.

• Focus attention on essential factors when comparing and contrasting alternatives.

• Facilitate open discussion about trade-offs among alternatives.

Activity Timing

Varies, depending on the number of alternatives and evaluation factors.

Participants

The architect is responsible for ensuring the matrix is filled in accurately. Stakeholders validate the evaluation factors.

Preparation and Materials

• Identify a list of architecturally significant requirements, especially quality attribute scenarios to be used as the properties for comparison.

• Before starting the analysis, identify at least two design alternatives for comparison.

Steps

1. Identify evaluation factors. Collaborate with stakeholders to agree on the factors used to compare and contrast alternatives.

2. Establish a rubric. Collaborate with stakeholders to decide how design alternatives will be scored. For guidance on defining a rubric, see ​Define a Design Rubric​.

3. Do the analysis and fill in the matrix.

4. Share the matrix with stakeholders. Verify the analysis and discuss your recommended decision.

Guidelines and Hints

• Use qualitative comparisons unless you performed quantitative analysis. For example, performance or availability can only be quantified if you ran tests.

• Consider no more than seven factors in the same matrix.

• Compare up to five design options in the same matrix. Use multiple matrices with a larger number of options.

• Take good notes when filling in the matrix. The analysis is as important as the results and can provide design rationale for decisions.

Example

Here is a sample decision matrix. Additional examples are shown in ​Create a Decision Matrix​.