methodatlas
Decision Making

PERT Estimation

Moves options, criteria, and risks toward a concrete result through "collect three values", "explain the formula", and "document the planning assumption".

Core question
What weighted expected value and confidence interval result from the three estimate values, and is that enough for the planning decision at hand?
MediumWorkshop + async15-45 min
Open runsheetPlan sessionStart comparison
Purpose

Helps clarify options, criteria, and risks in concrete terms. It separates options, evaluation criteria, and open risks. The result is captured as a PERT Estimate, Expected Value, and Risk Notes.

How it works

The team follows the steps "collect three values", "explain the formula", "calculate the expected value", "check variance or risk", and "document the planning assumption". Each step is made visible. At the end, PERT Estimate, Expected Value, and Risk Notes are available so decisions, tests, or actions can continue directly.

Visual orientation

Method sketch for a quick mental model.

PERT Estimation · gewichteter ErwartungswertOptimistischen, wahrscheinlichsten und pessimistischen Wert mit O plus 4M plus P geteilt durch 6 zu einer Planungsannahme verdichten
PERT EstimationDas Visual zeigt optimistischen, wahrscheinlichsten und pessimistischen Wert, die PERT-Formel und daraus abgeleitete Planungs- und Risikoinformation.Drei-Punkt-Schätzung zu einem gewichteten Erwartungswert verdichtenPERT nutzt dieselben drei Werte wie Three-Point Estimation, gewichtet den wahrscheinlichsten Wert aber stärker.O4OptimistischM8Most LikelyP16Pessimistischdrei Werte erhebenFormel transparent rechnenals Entscheidungsinputnutzen( O + 4M + P ) / 6wahrscheinlichster Wert wird vierfach gewichtet(4 + 4×8 + 16) / 6 = 8,7Expected Valuerobuster Planungswert, keine ZusageRisiko prüfenStreuung, Annahmen, externeAbhängigkeiten

Flow

  1. 1Collect three values
  2. 2Explain the formula
  3. 3Calculate the expected value
  4. 4Check variance or risk
  5. 5Document the planning assumption

The runsheet guides execution with 4 phases, timeboxes, 5 pitfalls, and clear stop criteria.

Open runsheet

Ideal for

  • Schedule and cost estimation
  • Project planning
  • Risk analysis

Not good for

  • Very small agile stories
  • Pure prioritization
  • Work without an expert baseline

Deep dive

In detail

PERT Estimation uses the same three values as Three-Point Estimation but gives the most likely value more weight. That produces an expected value that is less distorted by extremes than a simple average. The method can also consider variance or standard deviation to communicate schedule or cost risk. It remains an expert estimate and should not be mistaken for a precise prediction.

Facilitation

Explain the formula and the meaning of the three values up front. Calculate transparently and record assumptions, especially when pessimistic values are driven by dependencies or external risks. Use the numbers as decision input, not as a delivery promise.

Output artifacts
PERT EstimateExpected ValueRisk Notes
Tags
estimationprobabilityrisk

Sources

PERT Chart | Asanaasana.comPERT-Diagramm | Wrikewrike.com
Artifact templates
PERT Estimation Working TemplateCompact working template for PERT Estimation with context, input, output artifacts, and next step.
markdown

pert-estimation-working-template.md

Compact working template for PERT Estimation with context, input, output artifacts, and next step.

PERT Estimation Working Template

Goal

Weights three-point estimates, typically with the formula O plus 4M plus P divided by 6.

Context

When and for what do we use this method?

Input

Which data, observations, decisions, or materials are available?

Execution

Short notes along the runsheet.

Output artifacts

  • PERT Estimate:
  • Expected Value:
  • Risk Notes:

Assumptions and open questions

  • ...

Decision / Next step

Owner, date, and success signal.

When to choose differently

Short decision aid for existing alternatives.

Ideal Days

Statt PERT Estimation, wenn ihr Aufwand in reinen Arbeitstagen ausdrücken wollt und Teamkalibrierung beherrschbar halten möchtet.

Story Points

Statt PERT Estimation, wenn ihr relative Komplexität statt Kalenderzeit schätzen wollt und eure Schätzung im Team kalibrieren möchtet.

Similar methods

All methods
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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".

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Wideband Delphi

Moves options, criteria, and risks toward a concrete result through "clarify the estimate object and unit", "collect independent estimates", and "document another round and the outcome".

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Assumption Surfacing

Clarifies options, criteria, and risks by framing the initiative or decision, collecting implicit assumptions, and planning tests or research.

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Pre-Mortem

Turns options, criteria, and risks into a tangible result through defining the initiative, assuming failure, and assigning mitigations.

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Red Teaming

Turns options, criteria, and risks into a tangible result by defining scope, clarifying the Red Team role, and deriving mitigations.

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Risk Matrix

Moves options, criteria, and risks toward a concrete result through "set the scales for likelihood and impact", "collect risks or carry them over from earlier identification", and "define actions for each high-risk item".