The researchers came to their conclusion after analysing data collected through the American National Longitudinal Survey of Youth.

在对美国全国青年纵向调查搜集的数据进行分析之后，研究者们得出了上述结论。

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This same group also participated in an IQ test in 1980 as part of their enrollment in the National Longitudinal Survey of Youth.

同样是这群人还曾参加了1980年的一次IQ测试，作为国家青年长期追踪调查项目登记入伍的一部分。

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The teens were a subset of participants in the National Longitudinal Survey of Youth, a representative sample of American adolescents.

这些青少年是全美青少年纵贯调查协会(the Natiaonal Longitudinal Survey of Youth)的会员，是典型美国青少年的代表。

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The research, based on the US-wide National Education Longitudinal Survey, found that a teacher's gender had "large effects on student test performance".

BBC: NEWS | UK | Education | Male teachers 'better for boys'

So Dr. Mark Daniel DeBoer, an associate professor of pediatric endocrinology at the University of Virginia School of Medicine, and his colleagues turned to a large database of 10, 700 children in the Early Childhood Longitudinal Survey, Birth Cohort to investigate the relationship between the type of milk children drank and their body mass index (BMI).

CNN: Drinking skim milk may not lower child obesity risk

Here, a study called the Cebu Longitudinal Health and Nutrition Survey has been going on since 1983.

ECONOMIST: Vaccination