Estimate time and effort with an outside view instead of relying only on the current plan.
Open →Decision technique
Reference-class forecasting
Use outcomes from comparable completed cases before refining an inside-view plan.
When to use
A specific reasoning move for a specific problem.
For schedules, budgets, adoption forecasts and other repeatable predictions.
Procedure
Run the technique.
- Define the decision or quantity to forecast.
- Find a meaningful set of comparable completed cases.
- Use their distribution to set a baseline range.
- Adjust only for specific differences that can be defended with evidence.
Limit
What this technique cannot guarantee.
A bad comparison class can mislead. Similarity must be argued, not assumed.
Situations
Where this may be useful.
Make a forecast that can later be checked, updated and learned from.
Open →Evidence-linked concepts
Why this check may matter.
Practice this technique
See when the move becomes useful.
A team has a detailed task plan for a data migration. It predicts 40 days, but nobody has checked how long similar migrations actually took.
Skill: ForecastingOpen scenario →The previous project missed its date by six months. Managers now double every estimate, even though most comparable projects had much smaller delays.
Skill: ForecastingOpen scenario →