Tracing Mobile Phone App Installations in the “Friends and Family” Study Nadav Aharony, Wei Pan, Cory Ip, Alex (Sandy) Pentland MIT Media Laboratory, Cambridge 02139, MA, USA {nadav,panwei,coryip,pentland}@media.mit.edu Abstract The Friends and Family study in the MIT Media Lab is a long-term mobile phone-based experiment that transforms a graduate family community into a living lab for social science investigation. Data from this study, collected via Android-based phones equipped with our software platform for passive data collection, will be used to look at issues including individual and group identity, real world decision making, social diffusion, social health, and boundaries of privacy. In this paper we give an overview of the study and highlight some of the unique aspects that separate it from previous experiments, and report on some preliminary results from the recently concluded pilot phase. We focus our initial analysis on patterns surrounding mobile applications (apps). We look at participants’ app installation patterns and investigate the roles of different networks, inferred from Bluetooth proximity and self-reported surveys, in the spreading of apps. We find that face-to-face interactions have a stronger correlation with the number of shared apps between individuals than self-perceived ties. Introduction Today’s mobile phones are powerful computing and sensing platforms. We are investigating ways to help users leverage individual as well as aggregated data to improve their lives. Additionally, we are investigating how this data can contribute to the understanding of societal and especially community-related issues. The Human Dynamics Group in the MIT Media Lab has developed the methodology of Reality Mining, which is defined as the collection and analysis of machine-sensed environmental data pertaining to human social behavior [1] and is a key component in the transformation of traditional social science into the emerging field of computational social science [2]. To gather this data, we use our self- designed sensor platforms as well as smartphones. In recent years, we have performed two large-scale experiments on the MIT campus using close to one hundred phones each. The first study was performed in 2005 with participants from the MIT Media Lab and the Sloan School of Management, who represented a population of Media Lab colleagues and coworkers [1]. The second study was performed during the 2008-2009 academic year at an MIT undergraduate dorm during the 2008-2009 academic year, with a study population comprised of undergraduate students [3]. FunF Study Overview The Friends and Family study (FunF) is an experiment in the form of a living lab, with participants’ everyday behavior patterns sampled via mobile phones and other data collection mechanisms. The pilot phase of the study ran from March to July 2010 with 55 participants, and the expanded second phase of the study will begin in September 2010 with around 200 participants. The data collected pertains to both the physical and digital realms and includes information on face-to-face interactions, mobility, phone communication networks, and online social network activity. The study team also has direct access to the participants in the forms of questionnaires, interviews, and various experimental interventions, giving the FunF study access to a tight-knit physical community at an unprecedented scale and depth. Considering the study will run at least 18 months, the dataset generated from the study will shed light on a wide range of behavioral, social, and health-related topics. Study Goals The study touches on many aspects of life, from social dynamics to health to purchasing behavior to community organization. The two high-level topics that unify these varied aspects are: (a) how people make decisions, especially the social aspects involved in decision making, and (b) how we can empower people to make better decisions using personal and social tools. Study Components The study is composed four main components: Android Phone Sensing Platform (FunF System): This is the core of the study’s data collection. Android OS- based mobile phones are used as in-situ social sensors to map users’ activity features, proximity networks, media consumption, and behavior diffusion patterns. The phones