解决双向实验中部分单位可被分配处理的干扰效应估计问题
Estimating Total Effects in Bipartite Experiments with Spillovers and Partial Eligibility
- 区分可及与不可及单位,定义主次总处理效应
- 提出融合暴露映射与机器学习的低偏差估计方法
- 适用于有干扰且仅部分可处理的真实实验场景
我们研究双向系统中的随机实验,其中仅部分处理端单元具有分配资格,而所有单元仍保持互动,导致干扰。我们形式化了资格受限的双向实验,定义了与完全部署一致的估计量:对可及单位的主总处理效应(PTTE)和对不可及单位的次总处理效应(STTE)。在可及集合内随机化条件下,我们给出识别条件,并开发了融合暴露映射、广义倾向得分和灵活机器学习的干扰感知集成估计器。我们进一步引入一种将处理端与结果端估计量关联的投影,该映射在线性可加边条件下精确成立,可在通常更小的处理端实现确定性聚合。在具有已知真实值的模拟中,所提估计器对PTTE和STTE的估计偏差与方差均较低,且显著降低了忽略干扰时可能产生的偏差。两个实地实验表明其实际价值:方法在两项研究中均纠正了预期干扰偏差的方向,并在一个案例中逆转了主要决策指标的符号与显著性。
原文摘要 · Abstract (English)
We study randomized experiments in bipartite systems where only a subset of treatment-side units are eligible for assignment while all units continue to interact, generating interference. We formalize eligibility-constrained bipartite experiments and define estimands aligned with full deployment: the Primary Total Treatment Effect (PTTE) on eligible units and the Secondary Total Treatment Effect (STTE) on ineligible units. Under randomization within the eligible set, we give identification conditions and develop interference-aware ensemble estimators that combine exposure mappings, generalized propensity scores, and flexible machine learning. We further introduce a projection that links treatment- and outcome-level estimands; this mapping is exact under a Linear Additive Edges condition and enables estimation on the (typically much smaller) treatment side with deterministic aggregation to outcomes. In simulations with known ground truth across realistic exposure regimes, the proposed estimators recover PTTE and STTE with low bias and variance and reduce the bias that could arise when interference is ignored. Two field experiments illustrate practical relevance: our method corrects the direction of expected interference bias for a pre-specified metric in both studies and reverses the sign and significance of the primary decision metric in one case.
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