Are Circles Communities? A Comparative Analysis of Selective Sharing in Google+

The audience of shared content in Social Media is often hard to determine. To protect users from over-sharing, several services provide a feature for grouping contacts. Communities, interest groups, and circles are common examples. In this work, we investigate the structural properties of the circles in Google+ in comparison to the well-known communities. Based on several data sets and scoring functions, we search for the specific characteristics of circles. Our findings indicate that circles indeed form a special substructure that clearly differs from community groups. While the internal connectivity of circles and communities appear fairly similar, circles admit a much enhanced intensity of external relations. Circles resemble communities to which a large number of external links have been added. Selective sharing in circles is thus less confined.