The Coleman-Theil index (Burt 1992) measures how concentrated Burt's dyadic constraint is across the \(d_i\) contacts of node \(i\). Let \(p_{ij}\) be the share of the mutual tie strength of \(i\) invested in \(j\), \(c_{ij} = (p_{ij} + \sum_q p_{iq} p_{qj})^2\) the constraint, and \(r_{ij}\) the constraint divided by its mean over the contacts. Then $$H_i = \frac{\sum_{j \in N(i)} r_{ij} \log r_{ij}}{d_i \log d_i}.$$
Arguments
- x
Network input accepted by
centrality.- ...
Further arguments to
centrality. The measure usesweighted(use edge weights, defaultTRUE).
Details
The mutual tie strength of a pair is the sum of the weights in both
directions, so direction is combined and loops are removed. Edge weights
must be finite and nonnegative, and weighted = FALSE gives every
edge weight one before the directions are combined. The index lies
between zero, for equal constraints, and one, for constraint
concentrated on one contact. Following Burt's STRUCTURE 4.2 manual
(pages 181-183), an isolated node scores zero and a node with one
contact scores one. The organizational and oligopoly multipliers of
STRUCTURE are fixed at one. A weight range beyond double precision
raises an error.
References
Burt, R. S. (1992). Structural Holes: The Social Structure of Competition. Harvard University Press. doi:10.4159/9780674029095 .
