16–18 Jun 2025
Columbia University, Nevis Laboratories
America/New_York timezone

Unaccounted-for look-elsewhere effect in k-fold cross adaptive anomaly searches

17 Jun 2025, 11:30
15m
Nevis Science Center (Columbia University, Nevis Laboratories)

Nevis Science Center

Columbia University, Nevis Laboratories

Speaker

Prasanth Shyamsundar (Fermi National Accelerator Laboratory)

Description

Recently a technique based on k-fold cross validation has become popular in anomaly detection in HEP, as a way to search for a wide class of anomalies in the data, without paying an associated penalty in sensitivity-depth. In this work, we point out that the breadth-depth tradeoff is an unavoidable aspect of anomaly detection, and cannot be overcome using the aforementioned k-fold cross adaptive search technique. Furthermore, we show that the technique leads to unaccounted-for look-elsewhere effect, i.e., the underestimation of p-values or the overestimation of significances of observed anomalies.

Primary authors

Nicholas Smith (Fermi National Accelerator Laboratory) Prasanth Shyamsundar (Fermi National Accelerator Laboratory) Manuel Szewc (University of Cincinnati)

Presentation materials