发表机构
Mississippi State University（密西西比州立大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究针对吸收性治疗开始设计，提出有界与分位数零假设的随机化检验，证明其有限样本有效性，并揭示检验势由开始窗口而非序列长度决定，同时处理假设失效情形以支持敏感性分析。
AI 中文摘要
在多基线实验、交错采纳设计和阶梯楔形试验中，每个单元在随机化的开始时间从基线状态切换至治疗状态一次，并在之后保持治疗状态。我们将这些设计称为吸收性开始设计。由于此类实验通常仅涉及少数异质性单元，针对任何单元在任何时期均无效应的尖锐零假设的随机化检验十分常见。然而，拒绝该零假设仅意味着在某些地方存在某种效应，并不表明效应较大、对大多数单元-时期为正或具有持续性。我们研究在吸收性开始设计中，随机化检验能为有界零假设和分位数零假设下的单元-时期单元格效应确立何种结论。在假设单元格的潜在结果取决于其当前治疗状态而非治疗开始时间的条件下，我们为两种检验建立了有限样本有效性，并发展了有界零假设检验的势理论，其中单元数$N$固定，序列长度$T$增长且允许$K_T$个开始时间。针对固定备择假设的$p$值以$K_T^{-N}$的速度衰减，而非随$T$衰减，并具有匹配的下界，因此决定势的是开始窗口而非序列长度。我们还处理了该假设部分或完全失效的情形，这促使了敏感性分析。
英文摘要
In multiple-baseline experiments, staggered adoption designs, and stepped-wedge trials, every unit switches once from baseline to treatment at a randomized onset time and remains treated afterward. We label these designs as absorbing onset. Because such experiments often involve only a few heterogeneous units, randomization tests of the sharp null of no effect on any unit at any period are common. Rejecting this null, however, implies that some effect exists somewhere, not that it is large, positive for most unit-periods, or persistent. We study what randomization tests can establish for bounded nulls and quantile nulls on unit-period cell effects in absorbing onset designs. Under the assumption that a cell's potential outcome depends on its current treatment status and not on when treatment began, we establish finite-sample validity for both tests and develop the power theory for the bounded-null tests with a fixed number of units $N$ and a growing series length $T$ that admits $K_T$ onsets. The $p$-value against a fixed alternative decays as $K_T^{-N}$, not in $T$, with matching lower bounds, so the onset window, not the series length, determines the power. We also treat cases in which this assumption fails partially or completely, which motivates a sensitivity analysis.
