perevent

A perevent is a term used in time-series analysis and risk assessment to describe an event that occurs before a primary or target event within a causal sequence. It functions as an early indicator or potential trigger in predictive models, signaling elevated probability of the ensuing event without guaranteeing its occurrence. The concept is often used to distinguish signals that precede a main outcome from the main event itself.

The word perevent is formed from the idea of a pre-event preceding the principal event. In practice, perevents are identified and analyzed to improve forecasting, monitoring, or decision-making in fields such as engineering, epidemiology, finance, and cybersecurity. They are not assumed to be sufficient causes, but they may be statistically associated with the target event and provide lead time for interventions.

Formally, given a sequence of time-stamped events and a designated target event, a perevent is any event that occurs earlier in time than the target and exhibits a meaningful relationship with it. Lead time is defined as the temporal gap between the perevent and the target event, which can be leveraged to assess risk and implement preventive measures.

Modeling approaches for perevents include survival analysis with pre-event covariates, sequential pattern mining, hazard modeling, and Bayesian networks that capture temporal dependencies. Typical examples include minor sensor anomalies preceding a component failure, unusual access patterns preceding a security breach, or early clinical indicators preceding a health event.

Limitations include the risk of false positives, dependence on data granularity, and challenges in establishing causal meaning. See also precursor, antecedent, predictor, lead indicator, and event tree.