Randomization Tests for Distributions of Individual Treatment Effects via Combined Rank Statistics

Fuente: arXiv
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Main Authors: Kim, David, Su, Yongchang, Bowers, Jake, Li, Xinran
Format: Preprint
Published: 2026
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author Kim, David
Su, Yongchang
Bowers, Jake
Li, Xinran
author_facet Kim, David
Su, Yongchang
Bowers, Jake
Li, Xinran
contents What proportion of treated units actually benefited from an experimental intervention? What is the median or the largest individual treatment effect? This paper develops methods for answering such questions about the distribution of individual causal effects in randomized experiments. Existing approaches require the analyst to select a rank-based test statistic before observing the data. A poor choice can substantially reduce power, while searching over multiple test statistics and adjusting for multiplicity using Bonferroni correction also incurs power loss. We propose inference procedures that adaptively combine multiple rank-based statistics while maintaining finite-sample validity. For stratified experiments, we further develop weighting schemes that effectively aggregate evidence across strata of heterogeneous sizes. The resulting combined test achieves power comparable to, or exceeding, that of the best individual test, without requiring prior knowledge of the optimal statistic. When applied to a randomized experiment evaluating a teacher training program, the combined test suggests that roughly half of treated teachers benefited, whereas a single rank-based test may indicate only a small minority. Thus, the choice of test determined whether the program appears broadly successful or narrowly effective.
format Preprint
id arxiv_https___arxiv_org_abs_2605_08027
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Randomization Tests for Distributions of Individual Treatment Effects via Combined Rank Statistics
Kim, David
Su, Yongchang
Bowers, Jake
Li, Xinran
Methodology
Applications
What proportion of treated units actually benefited from an experimental intervention? What is the median or the largest individual treatment effect? This paper develops methods for answering such questions about the distribution of individual causal effects in randomized experiments. Existing approaches require the analyst to select a rank-based test statistic before observing the data. A poor choice can substantially reduce power, while searching over multiple test statistics and adjusting for multiplicity using Bonferroni correction also incurs power loss. We propose inference procedures that adaptively combine multiple rank-based statistics while maintaining finite-sample validity. For stratified experiments, we further develop weighting schemes that effectively aggregate evidence across strata of heterogeneous sizes. The resulting combined test achieves power comparable to, or exceeding, that of the best individual test, without requiring prior knowledge of the optimal statistic. When applied to a randomized experiment evaluating a teacher training program, the combined test suggests that roughly half of treated teachers benefited, whereas a single rank-based test may indicate only a small minority. Thus, the choice of test determined whether the program appears broadly successful or narrowly effective.
title Randomization Tests for Distributions of Individual Treatment Effects via Combined Rank Statistics
topic Methodology
Applications
url https://arxiv.org/abs/2605.08027