title: New perspectives on the "silo effect": initial comparisons of network structures across public health collaboratives.
abstract: OBJECTIVE
  We explored to what extent "silos" (preferential partnering) persist in interorganizational boundaries despite advances in working across boundaries. We focused on organizational homophily and resulting silo effects within networks that might both facilitate and impede success in public health collaboratives (PHCs).
  
  
  METHODS
  We analyzed data from 162 PHCs with a series of exponential random graph models to determine the influence of uniform and differential homophily among organizations and to identify the propensity for partnerships with similar organizations.
  
  
  RESULTS
  The results demonstrated a low presence (8%) of uniform homophily among networks, whereas a greater number (30%) of PHCs contained varying levels of differential homophily by 1 or more types of organization. We noted that the higher frequency among law enforcement, nonprofits, and public health organizations demonstrated a partner preference with similar organizations.
  
  
  CONCLUSIONS
  Although we identified only a modest occurrence of partner preference in PHCs, overall success in efforts to work across boundaries might be problematic when public health members (often leaders of PHCs) exhibit the tendency to form silos.
authors.affiliation: Christine A. Bevc is with the North Carolina Institute for Public Health, Gillings School of Global Public Health, University of North Carolina at Chapel Hill. Jessica H. Retrum is with the Department of Social Work, Metropolitan State University of Denver, CO. Danielle M. Varda is with the Research Program on Collaborative Governance and the School of Public Affairs, University of Colorado-Denver.
authors.forename: Christine A
authors.initials: CA
authors.lastname: Bevc
authors.forename: Jessica H
authors.initials: JH
authors.lastname: Retrum
authors.forename: Danielle M
authors.initials: DM
authors.lastname: Varda
mesh_terms: D003153:Community Health Services / Q000458:organization & administration*; D003299:Cooperative Behavior; D006801:Humans; D007373:Interinstitutional Relations; D007857:Leadership; D011635:Public Health Administration; D013597:Systems Analysis