# Option Comparison & Trade-off Analysis

Compares the options on the table against criteria someone else weighted — scoring only where there is evidence, and naming what would change the answer.

## Deliverable

One Markdown document, `option-comparison.md`, in the structure set out under **Output** below. It is the input to **Decision Record Authoring**.

## Required inputs

- **The decision to be made** — stated as a question with exactly one answer, with who asked it and when.
- **The options on the table** — at least two, each separately choosable.
- **The criteria that matter, with their weights** — supplied by the requester, not chosen here.

If any of the three is absent, stop and report it. Never invent a criterion or a weight: a weight the skill chose is the skill deciding, dressed as analysis.

## Optional inputs

- Evidence for any option: measurements, trials, references, vendor documentation
- Constraints that rule an option in or out: budget ceiling, deadline, regulation, contract
- The people affected by each option, and who must agree
- Options already rejected before this comparison, and why
- The date by which the decision must be made, and what is lost by missing it

Each absent optional input leaves its cell `unscored` rather than estimated; the matrix carries the gap and names the evidence that would close it.

## Execution

**1 — Restate the decision as a question.** Write the decision as a single question with exactly one answer, with its source and date. If the question can only be stated by naming one of the options, the decision has already been made elsewhere — write that down and continue.

**2 — Fix the option set.** One line per option, with what choosing it commits to. Include the option of doing nothing, because it is always available. Merge duplicates. Options that a supplied constraint rules out move to a separate list beside the constraint that ruled them out.

**3 — Record criteria and weights as supplied.** Copy each criterion and its weight verbatim, with who supplied it and when. A criterion with no weight is listed `unweighted`; the skill does not assign one.

**4 — Score only where there is evidence.** For each option-criterion pair: a score and the evidence that supports it, with its source. A pair with no evidence is marked `unscored` and never given a number. An unscored cell is information, not a hole to fill.

**5 — Assemble the matrix.** One line per option: the score for each criterion in order, or `unscored`, and the weighted total computed only from scored criteria. State how many criteria each total covers, because a high total over few criteria is not a high total.

**6 — Name the recommendation and its sensitivity.** The option the scored evidence supports, and the criteria whose change of weight would flip it. If a small change in one weight changes the answer, the decision rests on that weight and not on the evidence.

**7 — State what would change the recommendation.** For each unscored cell and each contested weight: the evidence that would settle it, who can produce it, and what getting it would take. Order by how far the answer would move.

## Output

`option-comparison.md`, in this order:

- **1. Decision** — the question, who asked it, when, and the date it must be answered by
- **2. Options** — one line each: name, what choosing it commits to, who proposed it
- **3. Criteria and weights** — criterion, weight, who supplied it, when; `unweighted` where none was given
- **4. Scores** — one line per option and criterion: the score or `unscored`, and the evidence with its source
- **5. Matrix** — one line per option: the scores in criteria order, the weighted total, and how many criteria that total covers
- **6. Recommendation** — the option, what the evidence supports, and what it does not
- **7. Sensitivity** — the criteria and weights whose change flips the recommendation
- **8. Evidence that would change the answer** — what is missing, who can produce it, what it would take
- **9. Rejected before scoring** — options excluded by a constraint, with the constraint and its source

## Validation

The comparison is ready when all of these hold:

- Section 1 states a question, not a preference
- Every option in section 2 appears in section 5, including doing nothing
- Every weight in section 3 names who supplied it; none was chosen by the skill
- Every score in section 4 carries evidence with a source; every cell without evidence reads `unscored`
- Section 5 states, per option, how many criteria its total covers
- Section 7 is non-empty, or states that no single change of weight flips the recommendation

Fail the run if any cell carries a number without evidence, or if a weight appears that no named person supplied.

## Failure handling

- **Only one option supplied** — add doing nothing as the second option and say so plainly. If the requester rejects that pairing, stop: a single option is a proposal, not a decision.
- **No weights supplied** — produce sections 1 to 5 with every criterion `unweighted`, report the scores criterion by criterion with no total, and name who must set the weights. Do not total unweighted criteria.
- **No access to the evidence** — mark every affected cell `unscored`, deliver the matrix with its gaps visible, and state that no option was compared on those criteria.
- **Contradictory evidence for one cell** — record both, name both sources, mark the cell `contested` and raise it in section 8. Do not average them.
- **Partial material** — score what the evidence supports, mark the rest `unscored`, and deliver. A matrix with honest gaps supports a decision; a full one built on guesses conceals who made it.