Weighted Decision Matrix
Options scored against weighted criteria — useful for making the reasoning inspectable, dangerous when the arithmetic is mistaken for the decision.
Options across the top, criteria down the side, weights agreed before anyone scores anything. The output is not the winning total; it is a visible record of what mattered and how each option was judged, which is what a reviewer can argue with.
The shape
| Criterion | Weight | A: Managed Kafka | B: Self-managed Kafka | C: Cloud pub/sub |
|---|---|---|---|---|
| Ordering guarantees needed | 25% | 5 — per-partition | 5 — per-partition | 2 — no global order |
| Replay / retention (30 days) | 20% | 5 | 5 | 2 — 7 days max |
| Operational burden | 20% | 4 — vendor runs it | 1 — needs 2 FTE | 5 — fully managed |
| Existing team skill | 10% | 3 | 3 | 2 |
| 3-year TCO | 15% | 2 — ₹3.4 cr | 3 — ₹2.6 cr + staff | 4 — ₹1.9 cr |
| Exit / portability | 10% | 4 — open protocol | 5 | 1 — proprietary API |
| Weighted total | 4.05 | 3.65 | 2.75 |
Decision: Option A. Why the number is not the reason: replay for 30 days is a hard requirement from the reconciliation process, and option C fails it outright at 2 — it should have been screened out before scoring rather than allowed to accumulate points elsewhere. Between A and B the totals are close enough to be noise; the deciding factor is that two dedicated operations staff do not exist and are not being funded.
When you produce it
For a contested decision with three or more genuine options and stakeholders who disagree about what matters. Not for a decision that is already obvious — the matrix will be reverse-engineered to justify it and everyone will know.
Who reads it
The review board, who should challenge the weights rather than the scores. Finance and procurement, in a vendor selection. The next architect, who needs to know what was actually being optimised for.
What good looks like
- Weights agreed and published before scoring. This is the entire integrity of the method.
- Hard requirements are screened first as pass or fail, not scored — otherwise an option that cannot meet a mandatory need wins on points elsewhere.
- Each score carries a one-line justification, as above.
- The narrative states the real reason, and says so where it differs from the arithmetic.
- Close totals are treated as ties, not as results.
Common mistakes
- Tuning the weights until the preferred option wins. Visible to everyone, and it destroys trust in every later matrix.
- Scoring mandatory requirements instead of screening on them.
- False precision — a total of 4.05 against 3.65 is not a meaningful margin.
- Presenting the matrix as the decision. It is the working; the judgement is still yours to make and to own.