title: Krackhardt E/I Ratio
text: # Krackhardt E/I Ratio
  
  The Krackhardt E/I Ratio (or variously the E-I Index) is a social network measure which the relative density of internal connections within a social group compared to the number of connections that group has to the external world. It was so described in a 1988 paper by David Krackhardt and Robert N. Stern noting the increased effectiveness in moments of crisis of organizations which had stronger informal networks that crossed formal internal group structures.
  
  ## Comparisons with network theory
  
  The E/I ratio is related to the concept of conductance, which measures the likelihood that a random walk on a subgraph will exit that subgraph.
  
  