11.4 Perform Quantitative Risk Analysis

Run the numbers on how the top risks could affect cost and schedule.

Planning / Risk · ← PMBOK reference · See it on the map

Why it matters

A ranked list tells you order but not scale; this puts an actual number on how much schedule or budget cushion the top risks genuinely justify.

What done looks like

A numeric analysis of the top risks' combined effect on cost and schedule exists.

First time tip

Reserve this deeper analysis for the highest-ranked risks only. Running it on every minor risk on the register costs more than it is worth.

What you need (Inputs)

• Risk Management Plan
• Scope Baseline
  How Scrum/Kanban projects satisfy this — counted from: committed backlog items and definition-of-done items (models/agile.py) — a committed backlog (status ready/in_progress/done) plus a written definition of done is what an agile team baselines scope against
• Schedule Baseline
  How Scrum/Kanban projects satisfy this — counted from: the current sprint's committed window (driftless/models/delivery.py:Sprint) for an agile project, or the department's own recurring work (driftless/models/operations.py:RecurringWork) for an operations-cadence one — an agile team's schedule is the sprint it has committed to, not a fixed baseline; an operations-cadence project's schedule is the cadence the department already runs
• Cost Baseline
• Risk Register
• Cost Estimates

How you do it (Tools & Techniques)

• Expert Judgment
• Representations of Uncertainty
• Simulation
• Sensitivity Analysis
• Decision Tree Analysis
• Influence Diagrams

What you get (Outputs)

• Risk Report

Worked example

For the two risks at the top, the committee works out what they would really cost. A washed-out day means refunding every ticket and still paying the stage hire, about three quarters of the budget, while a headline cancellation means paying a replacement act and selling fewer tickets. Sized and added together, they show the committee how large a contingency fund the ranked list alone never justified.

Common pitfalls

• Running the numbers on every entry in the register, which costs more volunteer time than the answer is worth.
• Presenting one figure as certain when it rests on a rough guess about ticket sales.
• Sizing the risks carefully and then setting the contingency fund by gut feel anyway.

How driftless helps

• Decision Tree Analysis can be run here.