https://phys.org/news/2018-07-boys-cliquey-girls.html

Led by the London School of Hygiene & Tropical Medicine (LSHTM) in partnership with the University of Cambridge, the study examined the features and structure of children's social networks within different schools. Previous research on social interactions among children has generally focused on just a single day. However, in this study the team surveyed the self-reported contacts of 460 year 7 pupils across four UK secondary schools over a five month period (between January and June 2015).

In total pupils completed 1,254 surveys, reporting contact information such as who they spend the most time with. The schools in the study were selected to be representative of different geographical and socioeconomic settings, for example including rural and urban and single-sex and mixed-sex schools.