中文摘要
助推干预已迅速从学术研究扩展到政府所谓“助推部门”中的更大规模实施。这为比较研究性干预与规模化实施的干预提供了机会。我们汇编了一个独特的数据集，包含126项随机对照试验（RCT），覆盖2300万人，其中包括美国两个最大助推部门开展的全部试验。我们将这些试验与近期两项荟萃分析所收录的学术期刊助推试验样本进行比较。在学术期刊论文中，助推的平均影响非常大——采纳率提高8.7个百分点，相当于较对照组平均值提高33.4%。在助推部门样本中，平均影响仍然可观且在统计上高度显著，但幅度较小，为1.4个百分点，相当于提高8.0%。我们记录了可以解释这两个估计值之差的三个维度：（i）试验的统计功效；（ii）干预的特征，如主题领域和行为渠道；以及（iii）选择性发表。纳入这些维度的荟萃分析模型表明，学术期刊样本中的选择性发表——其影响又因统计功效较低而加剧——解释了两个样本效应量差异的约70%。不同的助推特征解释了其余差异中的大部分。
Abstract
Nudge interventions have quickly expanded from academic studies to larger implementation in so‐called Nudge Units in governments. This provides an opportunity to compare interventions in research studies, versus at scale. We assemble a unique data set of 126 RCTs covering 23 million individuals, including all trials run by two of the largest Nudge Units in the United States. We compare these trials to a sample of nudge trials in academic journals from two recent meta‐analyses. In the Academic Journals papers, the average impact of a nudge is very large—an 8.7 percentage point take‐up effect, which is a 33.4% increase over the average control. In the Nudge Units sample, the average impact is still sizable and highly statistically significant, but smaller at 1.4 percentage points, an 8.0% increase. We document three dimensions which can account for the difference between these two estimates: (i) statistical power of the trials; (ii) characteristics of the interventions, such as topic area and behavioral channel; and (iii) selective publication. A meta‐analysis model incorporating these dimensions indicates that selective publication in the Academic Journals sample, exacerbated by low statistical power, explains about 70 percent of the difference in effect sizes between the two samples. Different nudge characteristics account for most of the residual difference.