Using unique administrative data from North Carolina that allow us to separate classroom teacher turnover during the school year from end-of-year turnover, we find students who lose their teacher during the school year have significantly lower test score gains (on average −7.5 percent of a standard deviation unit) than those students whose teachers stay. Moreover, the turnover of other teachers during the year lowers achievement gains, whereas end-of-year teacher turnover appears to have little effect on achievement. The harmful effects of within-year turnover cannot be explained by other extraneous shocks or the quality of departing teachers. Teachers who depart from December through April have the most harmful effects on achievement, although these vary somewhat by level of schooling and subject.

中文翻译：

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提前退学的后果：年内和年末教师更替的影响

利用北卡罗莱纳州的独特管理数据，我们可以将学年班主任与年末职员的流失分开，我们发现在学年中失去老师的学生考试成绩的提高明显较低（平均−7.5％的标准偏差单位）。此外，这一年其他教师的离职率降低了成就获得率，而年末教师的离职率似乎对成就没有太大影响。年内流失的有害影响无法用其他外来冲击或离任教师的素质来解释。从12月到4月离开的老师对成绩有最有害的影响，尽管这些影响因学历和科目的不同而有所不同。