Occupational selection and the reliability of position generator measures of social capital

This article investigates how variation in the social positions (occupations) presented by a position generator (PG) instrument affects the reliability of egocentric network measures based on PG data. We modify the split-half design employed in Verhaeghe et al.’s (2013) study of university students for use with already-existing PG data on a national adult population. After replicating that study, we examine how reliability varies with the relational criterion (e.g., friendship) that links an individual to an occupation and with the number of occupations in a PG. We find that most PG measures are only modestly reliable (i.e., are relatively sensitive to occupational selection), but our absolute assessment of their reliability (given instrument length) is somewhat more optimistic than that of the prior study. Extensity (the number of positions with which a subject has contact) is the most reliable measure, composition measures based on social class groupings are next, and those that involve socioeconomic standing or prestige scores are least reliable. Deeming someone to be connected to an occupation using an acquaintance criterion yields more reliable measures than requiring a stronger level of connectivity. PG measures based on longer (i.e., more occupations) instruments have higher reliability, and projections for longer PGs suggest that including 20 occupations could measure extensity and counts of contacts in some class groupings with adequate reliability; but other class composition measures and all measures involving socioeconomic standing or prestige scores would require 30 or more.