Social Capital in the United Kingdom: Evidence from Six Billion Friendships

Social capital is widely believed to impact a wide range of outcomes including subjective well-being, social mobility, and community health. We aggregate data on over 20 million Facebook users in the United Kingdom to construct several measures of social capital including cross-type connectedness, social network clustering, and civic engagement and volunteering. We find that social networks in the UK bridge class divides, with people below the median of the socioeconomic status distribution (low-SES people) having about half (47%) of their friendships with people above the median (high-SES people). Despite the presence of these cross-cutting friendships, we find evidence of homophily by class: high-SES people have a 28% higher share of high-SES friends. In part, this gap is due to the fact that high-SES individuals live in neighbourhoods, attend schools, and participate in groups that are wealthier on average. However, up to two thirds of the gap is due to the fact that high-SES people are more likely to befriend other high-SES peers, even within a given setting. Cross-class connections vary by region but are positively associated with upward income mobility: low-SES children who grew up in the top 10% most economically connected local authorities in England earn 38% more per year on average (£5,100) as adults relative to low-SES children in the bottom 10% local authorities. The relationship between upward mobility and connectedness is robust to controlling for other measures of social connection and neighbourhood measures of income, education, and health. We also connect measures of subjective well-being and related concepts with individual social capital measures. We find that individuals with more connections to high-SES people and more tightly-knit social networks report higher levels of happiness, trust, and lower feelings of isolation and social disconnection. We make our aggregated social capital metrics publicly available on the Humanitarian Data Exchange to support future research.