Purpose
A single opinion rarely holds up for planning when the future is genuinely uncertain. It separates options, evaluation criteria, and open risks. The result is captured as an Estimate Range, Assumption Log, and Expert Consensus Notes.
Decision Making Decision method
Wideband Delphi
Lets experts estimate independently, discusses differences, and narrows the range into viable planning.
Several experts estimate in parallel, compare their assumptions, and adjust after feedback. Ranges, uncertainty, and strong dissent become visible without forcing an apparent average. The approach strengthens planning discipline where numbers remain approximations.
What estimate range emerges when experts first estimate independently, compare assumptions anonymously, and re-estimate with new information?
- Participants
- 4-12 Experten
- Time
- 90–180 minutes for 2–4 anonymous estimation rounds; preparation separate.
The steps form one complete method run.
Brief
Shared scope
Coordinator explains scope, unit, and historical evidence; answers are shared equally.
Private
Round 1
Each expert independently estimates total or WBS parts and records assumptions and uncertainty.
Reflect
Anonymous summary
Coordinator shows distribution and rationales anonymously without making the mean a target.
Clarify
Clarified assumptions
Panel discusses reasons, updates shared scope, and identifies missing evidence without defending people.
Re-estimate
Delphi range
Estimate privately again; after stable spread, document range, assumptions, and review condition.
Add new evidence at review and version estimates with the prior state.
A good fit when
Bei unklaren Zukunftsfragen reicht eine Einzelmeinung selten für belastbare Planung. Wideband Delphi sammelt unabhängige Schätzungen und verdichtet sie zu einem nachvollziehbaren Bereich statt zu einer Scheingenauigkeit.
Ideal for
- Expert judgment
- Architecture effort
- Project or release estimation
Not good for
- Routine story estimation
- Very small tasks
- Teams without relevant expertise
Outputs
Delphi range
Traceable Delphi estimate with individual rounds, anonymous rationales, shared scope, residual spread, and review trigger.
Wideband Delphi · working structure
Fictional example
Fictional values show the actual method fields.
| Round/person | Estimate | Assumptions | Evidence | Anonymous feedback | Revision | Status |
|---|---|---|---|---|---|---|
| R1 · E1Add evidence and rationale. | 18 PD | No legacy migration | Token API exists | Range 18–30; migration disputed | 24 PD | Updated |
| R1 · E2Add evidence and rationale. | 24 PD | Five browsers, full tests | Last checkout item | Test scope confirmed | 26 PD | Updated |
| R1 · E3Add evidence and rationale. | 30 PD | Certification internal | Compliance experience | Certification external | 27 PD | Updated |
| OutcomeAdd evidence and rationale. | 24–27 PD | Migration included; certification external | Three private revisions | Residual spread from test depth | Review after migration probe | Stop rule met |
1. Estimate
- R1 · E1
- 18 PD
- R1 · E2
- 24 PD
- R1 · E3
- 30 PD
- Outcome
- 24–27 PD
2. Assumptions
- R1 · E1
- No legacy migration
- R1 · E2
- Five browsers, full tests
- R1 · E3
- Certification internal
- Outcome
- Migration included; certification external
3. Evidence
- R1 · E1
- Token API exists
- R1 · E2
- Last checkout item
- R1 · E3
- Compliance experience
- Outcome
- Three private revisions
4. Anonymous feedback
- R1 · E1
- Range 18–30; migration disputed
- R1 · E2
- Test scope confirmed
- R1 · E3
- Certification external
- Outcome
- Residual spread from test depth
5. Revision
- R1 · E1
- 24 PD
- R1 · E2
- 26 PD
- R1 · E3
- 27 PD
- Outcome
- Review after migration probe
6. Status
- R1 · E1
- Updated
- R1 · E2
- Updated
- R1 · E3
- Updated
- Outcome
- Stop rule met
All values are fictional.
First step
Close scope, unit, WBS, included work, and estimation question in writing; appoint a coordinator who does not estimate.
Deep dive
How it works
Several experts estimate in parallel, compare their assumptions, and adjust after feedback. This makes ranges, uncertainties, and firm dissenting positions visible without the group immediately settling on an apparent average. The method strengthens planning discipline wherever numbers are only approximations.
In detail
Wideband Delphi extends the Delphi idea with stronger interaction between estimation rounds. Experts first provide independent estimates, then the group surfaces ranges, outliers, and assumptions. The group discusses reasons for differences without exposing individuals. Additional rounds narrow the range or intentionally document remaining uncertainty.
Facilitation
Define scope, assumptions, and unit of measure up front. Collect the first values independently, document ranges, and discuss differences calmly. Do not force consensus if real uncertainty remains.
The method guide walks execution through 5 phases, timing, 5 pitfalls, and clear stop criteria.
Open method guideYour perspective
Does this method help with your work?
Your feedback helps shape the next improvements to methodatlas.
Sources and topics
Artifact templates
Wideband Delphi: WorksheetSet subject, data, roles, flow, and review.markdown
Wideband Delphi: WorksheetSet subject, data, roles, flow, and review.
markdownwideband-delphi-working-template.md
Set subject, data, roles, flow, and review.
Wideband Delphi: Worksheet
Question
To be confirmed
Desired outcome
To be confirmed
Scope
Complete run Time: 90–180 minutes for 2–4 anonymous estimation rounds; preparation separate.
Complete this worksheet on paper or in your own document during the work.
Preparation for this scope
Method setup
- Materials: Shared scope/WBS, Definition of Done, historical analogies, private estimate sheets, and anonymous round summary
- Roles: Coordinator facilitates · 3–7 expert estimators · scope owner answers · scribe records assumptions
- Advance information: Close scope, unit, WBS, included work, and estimation question in writing; appoint a coordinator who does not estimate.
- Overall time needed: 90–180 minutes for 2–4 anonymous estimation rounds; preparation separate.
- Setup: Prepare a workspace with Brief · Private · Reflect · Clarify · Re-estimate; separate example from live data.
Prepare for the work steps
Brief: Shared scope
- Close scope, unit, WBS, included work, and estimation question in writing; appoint a coordinator who does not estimate.
- Shared scope/WBS, Definition of Done, historical analogies, private estimate sheets, and anonymous round summary
Private: Round 1
- Shared scope
Reflect: Anonymous summary
- Round 1
Clarify: Clarified assumptions
- Anonymous summary
Re-estimate: Delphi range
- Clarified assumptions
Wideband Delphi · working structure
| Round/person | Estimate | Assumptions | Evidence | Anonymous feedback | Revision | Status |
|---|---|---|---|---|---|---|
| R1 · E1 | ||||||
| R1 · E2 | ||||||
| R1 · E3 | ||||||
| Outcome |
- R1 · E1: Add evidence and rationale.
- R1 · E2: Add evidence and rationale.
- R1 · E3: Add evidence and rationale.
- Outcome: Add evidence and rationale.
The blank worksheet contains prompts only.
Reference · original teaching example
Brief: Shared scope
Expected artifact: Shared scope
Coordinator explains scope, unit, and historical evidence; answers are shared equally.
Entry:
...
- Is everyone estimating the same work in the same unit?
Private: Round 1
Expected artifact: Round 1
Each expert independently estimates total or WBS parts and records assumptions and uncertainty.
Entry:
...
- Were values submitted independently with rationale?
Reflect: Anonymous summary
Expected artifact: Anonymous summary
Coordinator shows distribution and rationales anonymously without making the mean a target.
Entry:
...
- Are range and diverging assumptions visible?
Clarify: Clarified assumptions
Expected artifact: Clarified assumptions
Panel discusses reasons, updates shared scope, and identifies missing evidence without defending people.
Entry:
...
- Did the discussion create information rather than consensus pressure?
Re-estimate: Delphi range
Expected artifact: Delphi range
Estimate privately again; after stable spread, document range, assumptions, and review condition.
Entry:
...
- Is residual spread explainable and the stop rule met?
Open questions and next steps
...
Method guide: https://methodatlas.meierhoff-systems.de/en/methods/wideband-delphi/run-sheet
Alternatives and neighbors
Fitting alternatives with decision guidance, followed by other related methods.
Agile
Planning Poker
Instead of Wideband Delphi, choose Planning Poker when the team wants to estimate quickly and relatively, and anonymous expert rounds would be too heavyweight.
Delivery
Monte Carlo Forecasting
Instead of Wideband Delphi, choose Monte Carlo Forecasting when you want to plan with probabilities instead of individual estimates.
Decision Making
Three-Point Estimation
Moves options, criteria, and risks toward a concrete result through "clarify the estimate object", "determine the optimistic value", and "derive the range, expected value, and risks".
Decision Making
Delphi Method
Bundles expert estimates across rounds until ranges, consensus, and assumptions become solid enough.
Agile
Ideal Days
Moves backlog, sprint work, and team flow toward a concrete result through "explain the ideal day unit", "calibrate with a reference item", and "do not confuse it with calendar days".
Decision Making
Red Teaming
Examines an initiative from an opposing perspective, collects weaknesses, and derives prioritized mitigations.
Constraints and origin
HighWorkshop + async1-4 h or multiple rounds
Profile
- Method form
- Decision method
- Participants
- 4-12 Experten
- Time
- 1-4 h or multiple rounds
- Maturity
- Canonical
- Origin
- Barry Boehm and John A. Farquhar
Next up: PERT Estimation