Expert judgment is typically the crux of cost and schedule estimates but in the spectrum of the risk management process, quantification of expert judgment is the weakest area - Fred Raymond, Acquistion Review Quarterly - Spring 199., pp. 147-154
Making credible estimates in any domain, from software development to heavy construction starts with a model of where the risks come from - the risk drivers and their interactions and propagations.
Risk Management is Project Management for Adults - Tim Lister
All risk is created by uncertainty, and uncertainty comes in two forms - reducible (epistemic) and irreducible (aleatory), no decision can be made in the presence of those uncertainties without making estimates about the probabilistic and statistical behaviours of the uncertainties that create the risk.
Here's a Bibliography of risk management papers, books, and thesis Risk Management on Complex System of Systems.
