We estimate the magnitude of attrition bias for 10 randomized controlled trials (RCTs) in education. We make use of a unique feature of administrative school data in England that allows us to analyse post‐test academic outcomes for nearly all students, including those who originally dropped out of the RCTs we analyse. We find that the typical magnitude of attrition bias is 0.015 effect size units (ES), with no estimate greater than 0.034 ES. This suggests that, in practice, the risk of attrition bias is limited. However, this risk should not be ignored as we find some evidence against the common ‘Missing At Random’ assumption. Attrition appears to be more problematic for treated units. We recommend that researchers incorporate uncertainty due to attrition bias, as well as performing sensitivity analyses based on the types of attrition mechanisms that are observed in practice.

中文翻译：

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缺失，推测与众不同：量化教育评估中的失职风险

我们估计了教育中10项随机对照试验（RCT）的磨损偏倚的程度。我们利用英格兰行政管理学校数据的独特功能，使我们能够分析几乎所有学生的考试后学业成绩，包括最初从我们分析的RCT中辍学的学生。我们发现损耗损耗的典型幅度为0.015效应大小单位（ES），估计值不大于0.034 ES。这表明，在实践中，磨损偏倚的风险是有限的。但是，当我们发现一些证据反对常见的“随机丢失”假设时，不应忽略这种风险。对于处理过的单位，损耗似乎更成问题。我们建议研究人员考虑由于磨损偏见而带来的不确定性，