Johari window
n.— «To help gauge each risk’s likelihood and potential impact, some companies find it useful to create what’s known as a “Johari window.” You first assess each threat’s probability—from low to high—and assign it to one of four boxes along one axis. You then assess its potential impact—from light to severe—and place it in the appropriate box along the other axis. The resulting diagram lets you instantly identify high-likelihood, high-impact threats.» —“The Art Of And Science Of Bouncing Back” by Art Van Bodegraven, Kenneth B. Ackerman DC Velocity (North Attleboro, Mass.) Apr., 2006. (source: Double-Tongued Dictionary)
There’s a wikipedia article on this and the nohari window.