Randomization Inference When N Equals One

Fuente: arXiv
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Main Authors: Liang, Tengyuan, Recht, Benjamin
Format: Preprint
Published: 2023
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author Liang, Tengyuan
Recht, Benjamin
author_facet Liang, Tengyuan
Recht, Benjamin
contents N-of-1 experiments, where a unit serves as its own control and treatment in different time windows, have been used in certain medical contexts for decades. However, due to effects that accumulate over long time windows and interventions that have complex evolution, a lack of robust inference tools has limited the widespread applicability of such N-of-1 designs. This work combines techniques from experiment design in causal inference and system identification from control theory to provide such an inference framework. We derive a model of the dynamic interference effect that arises in linear time-invariant dynamical systems. We show that a family of causal estimands analogous to those studied in potential outcomes are estimable via a standard estimator derived from the method of moments. We derive formulae for higher moments of this estimator and describe conditions under which N-of-1 designs may provide faster ways to estimate the effects of interventions in dynamical systems. We also provide conditions under which our estimator is asymptotically normal and derive valid confidence intervals for this setting.
format Preprint
id arxiv_https___arxiv_org_abs_2310_16989
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Randomization Inference When N Equals One
Liang, Tengyuan
Recht, Benjamin
Methodology
Optimization and Control
Statistics Theory
N-of-1 experiments, where a unit serves as its own control and treatment in different time windows, have been used in certain medical contexts for decades. However, due to effects that accumulate over long time windows and interventions that have complex evolution, a lack of robust inference tools has limited the widespread applicability of such N-of-1 designs. This work combines techniques from experiment design in causal inference and system identification from control theory to provide such an inference framework. We derive a model of the dynamic interference effect that arises in linear time-invariant dynamical systems. We show that a family of causal estimands analogous to those studied in potential outcomes are estimable via a standard estimator derived from the method of moments. We derive formulae for higher moments of this estimator and describe conditions under which N-of-1 designs may provide faster ways to estimate the effects of interventions in dynamical systems. We also provide conditions under which our estimator is asymptotically normal and derive valid confidence intervals for this setting.
title Randomization Inference When N Equals One
topic Methodology
Optimization and Control
Statistics Theory
url https://arxiv.org/abs/2310.16989