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18–24 Aug 2024
Cairns, Queensland, Australia
Australia/Brisbane timezone

Can we do beyond Wilks theorem for significance calculation? Estimating p-values with importance sampling

19 Aug 2024, 17:30
30m
M6

M6

Oral H: Statistical Methods for Physics Analysis in the XXIst Century Statistical Methods for Physics Analysis in the XXI Century

Speaker

Francisco Matorras (Instituto de Fisica de Cantabria, Santander, IFCA (ES))

Description

Particle physics experiments often rely on statistical hypothesis testing to determine statements of discovery, evidence, or exclusion, typically assessed through p-values, "number of sigmas." However, in many cases, the significance is evaluated using asymptotic formulae based on Wilk's Theorem, without guarantees that its conditions are fulfilled. Alternatively, p-values can be assessed using simulations, "toy Monte Carlo" but extending this technique to achieve the customary 5-sigma threshold required for a discovery is often impractical.
To address this challenge, we propose a method based on importance sampling, which allows for estimation via simulation while reducing the required sample size by orders of magnitude. Specifically, we suggest sampling from a signal-like probability distribution, and we demonstrate that, for a broad range of scenarios, this approach optimally minimizes variance.
We will outline the mathematical proofs supporting this method and discuss its application to various synthetic examples. Additionally, we will explore the feasibility of implementing this approach in realistic experimental settings.

Primary author

Francisco Matorras (Instituto de Fisica de Cantabria, Santander, IFCA (ES))

Presentation materials