Sequentially-Rerandomized Switchback Experiments

Fuente: arXiv
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Auteurs principaux: Zeng, Zhenghao, Adjaho, Christopher, Bucarey, Alonso, Qin, Chao, Zhang, Ruixuan, Hoban, Paul, Johari, Ramesh, Wager, Stefan
Format: Preprint
Publié: 2026
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author Zeng, Zhenghao
Adjaho, Christopher
Bucarey, Alonso
Qin, Chao
Zhang, Ruixuan
Hoban, Paul
Johari, Ramesh
Wager, Stefan
author_facet Zeng, Zhenghao
Adjaho, Christopher
Bucarey, Alonso
Qin, Chao
Zhang, Ruixuan
Hoban, Paul
Johari, Ramesh
Wager, Stefan
contents Large-scale online platforms and marketplace systems often evaluate new policies through experiments that randomize treatment across operational units (e.g., geographies, regions, or clusters) over many time periods. In these settings, standard A/B testing can be inefficient or unreliable due to a limited number of units, substantial cross-unit heterogeneity, non-stationarity, and potential carryover across periods. We propose Sequentially-Rerandomized Switchback Experiments (SRSB), a new experimental design that helps mitigate these challenges. SRSB re-randomizes treatment at each time period such as to enforce balance on pre-specified prognostic variables constructed from past observations. In the absence of carryover, SRSB improves precision by leveraging temporal dependence through balancing lagged outcomes and covariates; we develop finite-sample randomization inference under a sharp null as well as asymptotic inference as the number of periods grows. We then extend SRSB to settings with first-order carryover and introduce a blocked SRSB variant that rerandomizes within strata defined by the previous treatment to form stable and comparable "stay" groups. Extensive simulations demonstrate the practical gains and robustness of SRSB relative to standard switchback designs.
format Preprint
id arxiv_https___arxiv_org_abs_2604_02489
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Sequentially-Rerandomized Switchback Experiments
Zeng, Zhenghao
Adjaho, Christopher
Bucarey, Alonso
Qin, Chao
Zhang, Ruixuan
Hoban, Paul
Johari, Ramesh
Wager, Stefan
Methodology
Large-scale online platforms and marketplace systems often evaluate new policies through experiments that randomize treatment across operational units (e.g., geographies, regions, or clusters) over many time periods. In these settings, standard A/B testing can be inefficient or unreliable due to a limited number of units, substantial cross-unit heterogeneity, non-stationarity, and potential carryover across periods. We propose Sequentially-Rerandomized Switchback Experiments (SRSB), a new experimental design that helps mitigate these challenges. SRSB re-randomizes treatment at each time period such as to enforce balance on pre-specified prognostic variables constructed from past observations. In the absence of carryover, SRSB improves precision by leveraging temporal dependence through balancing lagged outcomes and covariates; we develop finite-sample randomization inference under a sharp null as well as asymptotic inference as the number of periods grows. We then extend SRSB to settings with first-order carryover and introduce a blocked SRSB variant that rerandomizes within strata defined by the previous treatment to form stable and comparable "stay" groups. Extensive simulations demonstrate the practical gains and robustness of SRSB relative to standard switchback designs.
title Sequentially-Rerandomized Switchback Experiments
topic Methodology
url https://arxiv.org/abs/2604.02489