What is Quantitative Risk Analysis?
Quantitative risk analysis puts real numbers on the top-priority risks: Monte Carlo simulation for schedule/cost ranges, expected monetary value, decision trees, sensitivity analysis (the tornado diagram). Its output isn't a ranking — it's statements like "80% confidence of finishing by March 14" or "risk-adjusted cost is $4.2M."
It's optional and reserved for projects big enough to justify the effort and data. Skipping it on a small project is good tailoring; skipping it on a megaproject is malpractice.
Worked example
Before committing to a contractual go-live date, a bank runs Monte Carlo on its core-banking migration schedule: the deterministic plan says November 1, but only 35% of simulations finish by then; 85% finish by December 10. The bank signs for December 15 — and keeps its penalty clauses unexercised.