Social capital II: determinants of economic connectedness.

Low levels of social interaction across class lines have generated widespread concern and are associated with worse outcomes, such as lower rates of upward income mobility. Here we analyse the determinants of cross-class interaction using data from Facebook, building on the analysis in our companion paper. We show that about half of the social disconnection across socioeconomic lines-measured as the difference in the share of high-socioeconomic status (SES) friends between people with low and high SES-is explained by differences in exposure to people with high SES in groups such as schools and religious organizations.

Social capital I: measurement and associations with economic mobility.

Social capital-the strength of an individual's social network and community-has been identified as a potential determinant of outcomes ranging from education to health. However, efforts to understand what types of social capital matter for these outcomes have been hindered by a lack of social network data. Here, in the first of a pair of papers, we use data on 21 billion friendships from Facebook to study social capital.

Impacts of early ACA Medicaid expansions on physician participation.

Objective: To quantify impacts of early Affordable Care Act (ACA) Medicaid expansions on Medicaid participation for primary care physicians.

Data Sources: The study uses secondary Medicaid Analytic eXtract (MAX) data from the United States for 2009-2012, as well as secondary National Plan and Provider Enumeration System (NPPES) data from the United States for 2015.

Study Design: The study uses a quasi-experimental difference-in-differences study design where the policy change is Medicaid expansion in six states that adopted early ACA Medicaid expansions during 2010 and 2011: California, Connecticut, the District of Columbia, Minnesota, New Jersey, and Washington.