Swiss Cheese Model
A model of analyses of major accidents and catastrophic systems failures to reveal multiple, smaller failures leading up to the actual hazard. In the model, each slice of many slices of cheese represents a safety barrier or precaution relevant to a particular hazard with no single barrier being foolproof, they each have “holes”. For some serious events, even though the holes will align infrequently, even rare cases of harm (errors making it \"through the cheese\") will be unacceptable. In health care, such failure modes, in which slices of the cheese line up more often than one would expect if the location of their holes were independent of each other occur distressingly commonly.