Good allocations from bad estimates

ICLR 2026 Conference SubmissionAnonymous Authors
Treatment AllocationTreatment effectsSample complexityRCT
Abstract:

Conditional average treatment effect (CATE) estimation is the de facto gold standard for targeting a treatment to a heterogeneous population. The method estimates treatment effects up to an error ϵ>0\epsilon > 0 in each of MM different strata of the population, targeting individuals in decreasing order of estimated treatment effect until the budget runs out. In general, this method requires O(M/ϵ2)O(M/\epsilon^2) samples. This is best possible if the goal is to estimate all treatment effects up to an ϵ\epsilon error. In this work, we show how to achieve the same total treatment effect as CATE with only O(M/ϵ)O(M/\epsilon) samples for natural distributions of treatment effects. The key insight is that coarse estimates suffice for near-optimal treatment allocations. In addition, we show that budget flexibility can further reduce the sample complexity of allocation. Finally, we evaluate our algorithm on various real-world RCT datasets. In all cases, it finds nearly optimal treatment allocations with surprisingly few samples. Our work highlights the fundamental distinction between treatment effect estimation and treatment allocation: the latter requires far fewer samples.

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Overview

Overall Novelty Assessment

The paper contributes a sample-efficient allocation algorithm requiring O(M/ε) samples instead of the standard O(M/ε²) needed for full CATE estimation, alongside a theoretical framework based on ρ-regularity for smooth treatment effect distributions. It resides in the Sample-Efficient Allocation Algorithms leaf, which contains only two papers total including this work. This represents a relatively sparse research direction within the broader taxonomy of 45 papers across the field, suggesting the specific focus on sample complexity reduction for allocation (as distinct from estimation) remains underexplored.

The taxonomy reveals this work sits within Optimal Allocation Methods and Algorithms, adjacent to leaves addressing multi-arm treatments, fairness constraints, and ranking-based approaches. Neighboring branches include Heterogeneous Treatment Effect Estimation (covering machine learning methods and calibration) and Learning and Allocation under Uncertainty (addressing sequential learning and cost uncertainty). The sibling paper Treatment Allocation Uncertain Costs examines cost heterogeneity, while this work focuses on estimation-allocation tradeoffs. The scope note for this leaf explicitly excludes methods requiring full CATE estimation, positioning this contribution as fundamentally distinct from two-stage estimate-then-allocate approaches prevalent in adjacent categories.

Among 19 candidates examined across three contributions, none were identified as clearly refuting the core claims. The sample-efficient algorithm examined 2 candidates with no refutations; the ρ-regularity framework examined 10 candidates with none providing overlapping prior work; the instance-dependent optimality condition examined 7 candidates, again with no refutations. This limited search scope suggests the specific combination of sample complexity analysis, regularity conditions on treatment effect distributions, and allocation-focused optimality criteria may not have direct precedents in the examined literature, though the modest candidate pool leaves open the possibility of relevant work beyond the top-19 semantic matches.

Based on the limited search of 19 candidates and the sparse taxonomy leaf containing only one sibling paper, the work appears to occupy a relatively novel position within the sample-efficient allocation subfield. The absence of refutations across all contributions suggests distinctiveness in approach, though the small search scope and narrow leaf structure mean this assessment reflects local novelty within the examined literature rather than exhaustive field coverage. The taxonomy structure indicates this direction—separating allocation efficiency from estimation accuracy—remains less developed than adjacent areas like CATE estimation or fairness-constrained allocation.

Taxonomy

Core-task Taxonomy Papers
45
3
Claimed Contributions
19
Contribution Candidate Papers Compared
0
Refutable Paper

Research Landscape Overview

Core task: treatment allocation with limited budget under heterogeneous treatment effects. This field addresses how to optimally assign interventions when resources are constrained and individuals respond differently to treatment. The taxonomy reveals several main branches: Optimal Allocation Methods and Algorithms focuses on designing efficient assignment rules and sample-efficient procedures; Heterogeneous Treatment Effect Estimation develops techniques to predict individual-level causal impacts; Learning and Allocation under Uncertainty tackles sequential decision-making where treatment effects must be learned while allocating; Application Domains explores real-world contexts from healthcare to marketing; Technical Infrastructure covers system-level considerations; and Specialized Allocation Problems examines settings with additional constraints like fairness or cost heterogeneity. Works like Optimal Treatment Budget Constraints[7] and Treatment Allocation Uncertain Costs[3] illustrate how budget limitations shape allocation strategies, while methods such as Calibration Heterogeneous Treatment Effects[6] and Direct Heterogeneous Causal Learning[18] address the estimation challenges underlying personalized assignment. A central tension runs through this literature: balancing the quality of treatment effect estimates against the efficiency of allocation decisions. Some lines emphasize learning accurate heterogeneous effects before deploying policies, as in Budgeted Treatment Effect Estimation[9] and Causal Machine Learning Theory[16], while others prioritize direct optimization of allocation rules even with imperfect estimates, exemplified by Learning to Rank Treatment[17] and Cost Effectiveness Treatment Rule[21]. Good Allocations Bad Estimates[0] sits within the Sample-Efficient Allocation Algorithms cluster, closely aligned with Treatment Allocation Uncertain Costs[3], both examining how allocation performance depends on estimation accuracy and sample efficiency. Where Treatment Allocation Uncertain Costs[3] emphasizes uncertainty in costs themselves, Good Allocations Bad Estimates[0] appears to explore the broader question of when allocation quality can be preserved despite estimation error, a theme that resonates with recent work on calibration and robust policy learning across multiple branches.

Claimed Contributions

Sample-efficient allocation algorithm requiring O(M/ε) samples

The authors develop an allocation algorithm that achieves near-optimal treatment allocation using O(M/ε) samples instead of the O(M/ε²) samples required by standard CATE estimation, demonstrating a quadratic improvement in sample complexity for smooth distributions of treatment effects.

2 retrieved papers
Theoretical framework based on ρ-regularity for smooth distributions

The authors introduce the concept of ρ-regularity as a smoothness condition on treatment effect distributions and prove that under this condition, coarse estimates with accuracy ρ = Θ(√ε) suffice for near-optimal allocation, formalizing when allocation requires fewer samples than estimation.

10 retrieved papers
Instance-dependent optimality condition for treatment allocation

The authors establish a necessary and sufficient condition on the CDF of treatment effect values that determines when their algorithm achieves (1−ε)-optimal allocation, providing a precise characterization that can be verified from low-accuracy estimates without requiring additional samples.

7 retrieved papers

Core Task Comparisons

Comparisons with papers in the same taxonomy category

Contribution Analysis

Detailed comparisons for each claimed contribution

Contribution

Sample-efficient allocation algorithm requiring O(M/ε) samples

The authors develop an allocation algorithm that achieves near-optimal treatment allocation using O(M/ε) samples instead of the O(M/ε²) samples required by standard CATE estimation, demonstrating a quadratic improvement in sample complexity for smooth distributions of treatment effects.

Contribution

Theoretical framework based on ρ-regularity for smooth distributions

The authors introduce the concept of ρ-regularity as a smoothness condition on treatment effect distributions and prove that under this condition, coarse estimates with accuracy ρ = Θ(√ε) suffice for near-optimal allocation, formalizing when allocation requires fewer samples than estimation.

Contribution

Instance-dependent optimality condition for treatment allocation

The authors establish a necessary and sufficient condition on the CDF of treatment effect values that determines when their algorithm achieves (1−ε)-optimal allocation, providing a precise characterization that can be verified from low-accuracy estimates without requiring additional samples.