Classroom teachers in the US are absent on average approximately six percent of a school year. Despite the prevalence of teacher absences, surprisingly little research has assessed the key source of replacement instruction: substitute teachers. Using detailed administrative and survey data from a large urban school district, we document the prevalence, predictors, and distribution of substitute coverage across schools. Less advantaged schools systematically exhibit lower rates of substitute coverage compared with peer institutions. Observed school, teacher, and absence characteristics account for only part of this school variation. In contrast, substitute teachers' preferences for specific schools, mainly driven by student behavior and support from teachers and school administrators, explain a sizable share of the unequal distribution of coverage rates above and beyond standard measures in administrative data.

中文翻译：

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不仅仅是不足：替代教学的分配不均

美国的课堂老师平均每学年缺勤6％。尽管教师缺席的情况很普遍，但令人惊讶的是，很少有研究评估替代教学的关键来源：替代教师。使用来自大型市区学区的详细行政和调查数据，我们记录了学校范围内替代品覆盖率的发生率，预测指标和分布。与同等院校相比，优势欠佳的学校系统地显示出较低的替代率。观察到的学校，教师和缺勤特征仅占这种学校变化的一部分。相比之下，主要由学生的行为以及老师和学校管理员的支持，替代教师对特定学校的偏好，