noun: outlier; plural noun: outliers
a person or thing situated away or detached from the main body or system.
“less accessible islands and outliers”
a person or thing excluded from a group; an outsider.
a younger rock formation isolated among older rocks.
a data point on a graph or in a set of results that is very much bigger or smaller than the next nearest data point.
Black swan theory
From Wikipedia, the free encyclopedia
A black swan, a member of the species Cygnus atratus
The black swan theory or theory of black swan events is a metaphor that describes an event that comes as a surprise, has a major effect, and is often inappropriately rationalized after the fact with the benefit of hindsight.
The theory was developed by Nassim Nicholas Taleb to explain:
The disproportionate role of high-profile, hard-to-predict, and rare events that are beyond the realm of normal expectations in history, science, finance, and technology
The non-computability of the probability of the consequential rare events using scientific methods (owing to the very nature of small probabilities)
The psychological biases that make people individually and collectively blind to uncertainty and unaware of the massive role of the rare event in historical affairs
Unlike the earlier philosophical “black swan problem,” the “black swan theory” refers only to unexpected events of large magnitude and consequence and their dominant role in history. Such events, considered extreme outliers, collectively play vastly larger roles than regular occurrences. More technically, in the scientific monograph Lectures on Probability and Risk in the Real World: Fat Tails (Volume 1), Taleb mathematically defines the black swan problem as “stemming from the use of degenerate metaprobability”.