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

We construct a range of measures of social capital (the strength and structure of social networks) for the United Kingdom using data from Facebook covering 20.5 million adults. We make these measures publicly available. Low-socioeconomic-status (SES) individuals have far fewer high-SES friends than high-SES individuals do. Areas with more cross-SES friendships display higher levels of intergenerational economic mobility (higher adult earnings for children growing up in disadvantaged families). Most of the difference in connectedness to high-SES individuals between low- and high-SES individuals is due to differences in friending bias---the tendency of people to befriend others similar to themselves even conditional on the possible friends they are exposed to. Areas with more long ties (friendships between people with no mutual connections) also display substantially higher levels of intergenerational economic mobility, and long ties are especially likely to form outside the typical settings in which individuals make friends. The relationships between economic connectedness, long ties, and intergenerational economic mobility remain strong even after controlling for other area-level characteristics. We also make new estimates of intergenerational economic mobility in the UK publicly available, including the first estimates for areas in Scotland and Northern Ireland.