Rare events


Rare or extreme events are events that occur with low frequency, and often refers to infrequent events that have widespread impact and which might destabilize systems. Rare events encompass natural phenomena, anthropogenic hazards, as well as phenomena for which natural and anthropogenic factors interact in complex ways.

Overview

Rare or extreme events are discrete occurrences of infrequently observed events. Despite being statistically improbable, such events are plausible insofar as historical instances of the event have been documented.
Scholarly and popular analyses of rare events often focus on those events that could be reasonably expected to have a substantial negative impact on a society—either economically or in terms of human casualties. Examples of such events might include an 8.0+ Richter magnitude earthquake, a nuclear incident that kills thousands of people, or a 10%+ single-day change in the value of a stock market index.

Modeling and analysis

Rare event modeling refers to efforts to characterize the statistical distribution parameters, generative processes, or dynamics that govern the occurrence of statistically rare events, including but not limited to high-impact natural or human-made catastrophes. Such “modeling” may include a wide range of approaches, including, most notably, statistical models derived from historical event data and computational software models that attempt to simulate rare event processes and dynamics. REM also encompasses efforts to forecast the occurrence of similar events over some future time horizon, which may be of interest for both scholarly and applied purposes.

Relevant data sets

In many cases, rare and catastrophic events can be regarded as extreme-magnitude instances of more mundane phenomena. For example, seismic activity, stock market fluctuations, and acts of organized violence all occur along a continuum of extremity, with more extreme-magnitude cases being statistically infrequent. Therefore, rather than viewing rare event data as its own class of information, data concerning “rare” events often exists as a subset of data within a broader parent event class.
The following is a list of data sets focusing on domains that are of broad scholarly and policy interest, and where “rare” cases may be of particularly keen interest due to their potentially devastating consequences.
Descriptions of the data sets are extracted from the source websites or providers.