Dual Degree Ph.D. Student Qiwei Han Wins Best Paper Award

  Qiwei Han, a dual degree Ph.D. student in Engineering and Public Policy at Instituto Superior Técnico of the Universidade de Lisboa (IST-UL) and Carnegie Mellon University (CMU), has received a Best Paper Award for the paper “Role of Peer Influence in Churn in Wireless Networks,” at the 7th ASE International Conference on Social Computing, the premier international forum for research on Information and Communication Technologies that consider social context.

The winning paper was co-authored by Qiwei Han’s advisor at CMU Pedro Ferreira, and it addresses the problem of subscriber churn, which is the biggest problem for wireless carriers. The authors explain on the abstract that “carriers need to understand the determinants of churn to confidently apply effective retention strategies to ensure their profitability and growth." In this paper, they "look at the effect of peer influence on churn and (…) try to disentangle it from other effects that drive simultaneous churn across friends but that do not relate to peer influence.” Using a random sample of roughly 10 thousand subscribers from a large dataset from a major Portuguese wireless carrier over a period of 10 months, the authors applied “survival models and generalized propensity score to identify the role of peer influence," showing that "the propensity to churn increases when friends do and that it increases more when many strong friends churn.” According to the authors, the “results suggest that churn managers should consider strategies aimed at preventing group churn,” adding that “survival models fail to disentangle homophily from peer influence over-estimating the effect of peer influence.” 

“Our paper provides a well-established methodology that disentangle peer influence from homophily and shows that even after controlling for confounding factors, we still see a positive effect of peer influence on churn,” Qwiei Han explained. 

“This collaboration with the Portuguese wireless carrier was fundamental and could not have happened if it weren’t for the CMU Portugal Program,” the student states, adding that “I personally think that this is an important milestone for our work and the award certainly shows that what we are doing has been recognized in the field for its quality.” Qiwei Han enrolled in 2010-2011 and is also advised by João Paulo Costeira (IST-UL). 

The ASE International Conference on Social Computing was held in held in Tsinghua University, in Beijing, China, between August 4 and 7, 2014. The acceptance rate since inception is quite selective, with only about 9.9% (2013) acceptance.  


September 2014
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Title: “The Role of Peer Influence in Churn in Wireless Networks”  

Authors: Qiwei Han (IST-UL and CMU) and Pedro Ferreira (CMU)

Abstract: Subscriber churn remains a top challenge for wireless carriers. These carriers need to understand the determinants of churn to confidently apply effective retention strategies to ensure their profitability and growth. In this paper, we look at the effect of peer influence on churn and we try to disentangle it from other effects that drive simultaneous churn across friends but that do not relate to peer influence. We analyze a random sample of roughly 10 thousand subscribers from large dataset from a major wireless carrier over a period of 10 months. We apply survival models and generalized propensity score to identify the role of peer influence. We show that the propensity to churn increases when friends do and that it increases more when many strong friends churn. Therefore, our results suggest that churn managers should consider strategies aimed at preventing group churn. We also show that survival models fail to disentangle homophily from peer influence over-estimating the effect of peer influence.