  The wide adoption of smartphones and mobile applications has brought
significant changes to not only how individuals behave in the real world, but
also how groups of users interact with each other when organizing group events.
Understanding how users make event decisions as a group and identifying the
contributing factors can offer important insights for social group studies and
more effective system and application design for group event scheduling.
  In this work, we have designed a new mobile application called
OutWithFriendz, which enables users of our mobile app to organize group events,
invite friends, suggest and vote on event time and venue. We have deployed
OutWithFriendz at both Apple App Store and Google Play, and conducted a
large-scale user study spanning over 500 users and 300 group events. Our
analysis has revealed several important observations regarding group event
planning process including the importance of user mobility, individual
preferences, host preferences, and group voting process.
