THE SHORT ANSWER
Define the decision and objective, record evidence, expose assumptions and uncertainty, generate real options, compare consequences and reversibility, decide with a review trigger, then evaluate both the outcome and the quality of the original process.
DEFINE → EVIDENCE → ASSUMPTIONS → OPTIONS → RISKS → DECIDE → REVIEW
| Step | Question |
|---|---|
| Define | What decision am I actually making, for which objective? |
| Evidence | What do I know, and how do I know it? |
| Assumptions | What am I treating as true or stable? |
| Options | What alternatives include waiting or doing less? |
| Risks | What are the consequences, uncertainties and safeguards? |
| Decide | What will I do, and what would change the decision? |
| Review | When and how will I examine the result and process? |
Generate options before comparing them
A binary choice can hide a smaller experiment, staged commitment, different timing or business-as-usual option. Generate alternatives against the objective before a favourite solution becomes the anchor.
The Green Book similarly separates objectives, option generation, appraisal, monitoring and evaluation. This framework adapts that reasoning rather than reproducing public-sector appraisal.
Evidence & context: HM Treasury and Government Finance Function
Information quality and decision quality are different
Accurate information does not select objectives, risk tolerance or ethical trade-offs. Conversely, a decision made with incomplete information can still be well reasoned if uncertainty, alternatives and safeguards were handled proportionately.
Judge the process using what was reasonably knowable at the time. Do not let a lucky outcome rewrite a weak decision as wise, or an unlucky outcome erase sound reasoning.
Write one page before deciding
- Decision and objective
- Known evidence and source
- Key assumptions
- Material unknowns
- Options considered
- Downside, upside and reversibility
- Chosen action and owner
- Change trigger and review date
Sources & further reading
- The Green Book 2026
HM Treasury and Government Finance Function. Current official guidance on objectives, options, evidence, risk, uncertainty, appraisal and evaluation. It is designed for public decisions, while the general reasoning principles are adapted here.
- Reproducibility and Replicability in Science
National Academies of Sciences, Engineering, and Medicine. A consensus report on evidence, uncertainty, transparency, reproducibility and replication. Scientific standards need proportionate adaptation outside research settings.
Examples and exercises are illustrative unless attributed to a source. No independent expert review is claimed.
A correction, a counterexample or an experience worth sharing?
Join the conversation ↗