Community detection in networks with positive and negative links

Detecting communities in complex networks accurately is a prime challenge, preceding further analyses of network characteristics and dynamics. Until now, community detection took into account only positively valued links, while many actual networks also feature negative links. We extend an existing Potts model to incorporate negative links as well, resulting in a method similar to the clustering of signed graphs, as dealt with in social balance theory, but more general. To illustrate our method, we applied it to a network of international alliances and disputes. Using data from 1993--2001, it turns out that the world can be divided into six power blocs similar to Huntington's civilizations, with some notable exceptions.Comment: 7 pages, 2 figures. Revised versio

Searching for relevance:NGO–donor relationships in a geographically isolated community

This study investigates the practice of NGO (nongovernment organizations)–donor relationships in a geographically isolated community in Alaska and explores the role of social capital in NGO sustainability. We employ the following parameters to apply social capital concepts to the needs of practitioners: study design centered on variables that are relevant for practitioners, nonlinear production of knowledge, attention to specifics of the context within which agents operate, and transfer of knowledge through the practitioners’ frame of reference. This study reveals that NGOs’ bonding social ties are of primary importance for assuring active donor commitment, while bridging ties serve to secure continuing commitment and support from passive donors. The structural, relational, emotional, and behavioral social capital dimensions shape both bonding and bridging ties, though they differ in their nature. Active donor commitment is increased by strengthening and extending the circle of bonding ties

Assessing the Effects of Personal Characteristics and Context on U.S. House Speakers’ Leadership Styles, 1789-2006

Research on congressional leadership has been dominated in recent decades by contextual interpretations that see leaders’ behavior as best explained by the environment in which they seek to exercise leadership—particularly, the preference homogeneity and size of their party caucus. The role of agency is thus discounted, and leaders’ personal characteristics and leadership styles are underplayed. Focusing specifically on the speakers of the U.S. House of Representatives from the first to the 110th Congress, we construct measures of each speaker’s commitment to comity and leadership assertiveness. We find the scores reliable and then test the extent to which a speaker’s style is the product of both political context and personal characteristics. Regression estimates on speakers’ personal assertiveness scores provide robust support for a context-plus-personal characteristics explanation, whereas estimates of their comity scores show that speakers’ personal backgrounds trump context