Group chats on Twitter

We report on a new kind of group conversation on Twitter that we call a group chat. These chats are periodic, synchronized group conversations focused on specific topics and they exist at a massive scale. The groups and the members of these groups are not explicitly known. Rather, members agree on a hashtag and a meeting time (e.g, 3pm Pacific Time every Wednesday) to discuss a subject of interest. Topics of these chats are numerous and varied. Some are support groups, for example, post-partum depression and mood disorder groups. Others are about a passionate interest: topics include skiing, photography, movies, wine and foodie communities. We develop a definition of a group that is inspired by how sociologists define groups and present an algorithm for discovering groups. We prove that our algorithms find all groups under certain assumptions. While these groups are of course known to the people who participate in the discussions, what we do not believe is known is the scale and variety of groups. We provide some insight into the nature of these groups based on over two years of tweets. Finally, we show that group chats are a growing phenomenon on Twitter and hope that reporting their existence propels their growth even further.