Here, we review the research we have done on social contagion. We describe
the methods we have employed (and the assumptions they have entailed) in order
to examine several datasets with complementary strengths and weaknesses,
including the Framingham Heart Study, the National Longitudinal Study of
Adolescent Health, and other observational and experimental datasets that we
and others have collected. We describe the regularities that led us to propose
that human social networks may exhibit a "three degrees of influence" property,
and we review statistical approaches we have used to characterize
inter-personal influence with respect to phenomena as diverse as obesity,
smoking, cooperation, and happiness. We do not claim that this work is the
final word, but we do believe that it provides some novel, informative, and
stimulating evidence regarding social contagion in longitudinally followed
networks. Along with other scholars, we are working to develop new methods for
identifying causal effects using social network data, and we believe that this
area is ripe for statistical development as current methods have known and
often unavoidable limitations.

本论文综述了对社会传染病进行的研究，提出了人际社交网络可能表现出 “三度影响” 的属性，还回顾了社交网络数据中使用的统计方法以及当前的局限性，强调了发展新的方法来识别社交网络数据中的因果效应的重要性。