In another life, I had the opportunity to contribute to a project for the U.S. Airforce. The base I was working with did landing gear maintenance for a number of aircraft from around the world. They wanted a quick and easy way to review individual landing gear parts and determine if they could be safely refurbished. Basically it was an established measuring process to ensure that after machining, the parts would still fall within specifications. After taking a number of very specific measurements to determine whether or not there was a possibility of successfully re-machining the part—if the part didn't meet pre-determined success criteria, it was scraped. The Airforce didn't want to waste time refurbishing a part that didn't offer a reasonable possibility of being usable upon completion. It was a very simple go-no-go method of measuring potential risk vs reward. Hospital emergency rooms use the same kind of triage procedure when evaluating which patients are seen first and who can wait.
I agree with Hillson when he suggests that the importance of prioritizing risk is not to obtain a precise estimate of the exact likelihood of a particular risk, but to focus on those that require urgent management, then deal with other important risks, and monitor others. A complex risk assessment isn't necessary to accomplish that. Successful project management doesn't require us to seek for more detail than what we need for this purpose.
Successful work management methodologies identify and prioritize risk, but don't necessarily dwell on whether or not a particular risk has a 10 percent, 12 percent, or even a 15 percent probability of occurring. "Even when generic scales are used," says Hillson, "people can spend a lot of time disputing between rating a risk as Low or Medium."
Project management software can help organizations evaluate risks, create mitigation plans, and successfully plan projects that fall into a predetermined success criteria.
Leonardo da Vinci wrote, "Simplicity is the ultimate sophistication."
When it comes to project prioritization maybe that is good advice.