National Congregations Study Method

The National Congregations Study (NCS) method solves a hard sampling problem: there is no complete list of all the congregations in a country, so they cannot be sampled directly. Mark Chaves and colleagues addressed this with hypernetwork (multiplicity) sampling - drawing a representative sample of individuals, asking those who attend services to name their congregation, and treating each named congregation as a sampled unit. Because a congregation is named in proportion to the number of people who attend it, this procedure automatically yields a sample of congregations with probability proportional to size, from which leaders are then interviewed. First fielded in 1998 and described in the 1999 Journal for the Scientific Study of Religion article, and repeated in later waves summarized in Chaves and Eagle's 2015 report, the NCS has become the standard way to produce nationally representative data on American congregations.