  The strength of social relations has been shown to affect an individual's
access to opportunities. To date, however, the correspondence between tie
strength and population's economic prospects has not been quantified, largely
because of the inability to operationalise strength based on Granovetter's
classic theory. Our work departed from the premise that tie strength is a
unidimensional construct (typically operationalized with frequency or volume of
contact), and used instead a validated model of ten fundamental dimensions of
social relationships grounded in the literature of social psychology. We built
state-of-the-art NLP tools to infer the presence of these dimensions from
textual communication, and analyzed a large conversation network of 630K
geo-referenced Reddit users across the entire US connected by 12.8M social ties
created over the span of 7 years. We found that unidimensional tie strength is
only weakly correlated with economic opportunities (R2=0.30), while
multidimensional constructs are highly correlated (R2=0.62). In particular,
economic opportunities are associated to the combination of: i) knowledge ties,
which bridge geographically distant groups, facilitating the knowledge
dissemination across communities; and ii) social support ties, which knit
geographically close communities together, and represent dependable sources of
social and emotional support. These results point to the importance of
developing high-quality measures of tie strength in network theory.
