TheStrengthofWeakTies

Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,*,The Strength of Weak Ties,Mark S. Granovetter,The American Journal of Sociology, 1973,Slides Prepared By: Andrew Miklas,1,Introduction,“One of the most influential sociology papers ever written” (Barabasi),One of the most cited (,Current Contents, 1986),Interviewed people and asked:“How did you find your job?”,Kept getting the the same answer: “through an acquaintance, not a friend”,2,Context,Lots of studies of macro patterns,Social mobility, community organization,Data and studies for micro behavior,Interactions within small groups,Limited understanding of how micro behavior translates into macro patterns,3,Network Analysis,Analysis of the interaction network,bridge the gap between micro and macro,Interaction network,Nodes:,People,Edges:,Between people with a social relationship,Weight:,strength of connectionQuantize to either “weak” or “strong”,4,Bridges,Bridge:,An edge that is part of every path between two nodes,Bridge b/w red & green,5,Local Bridges,Local Bridge of degree N:,An edge that is part of every path of length less than N,Generalization of a bridge,Local bridge of deg 3b/w A & B,A,B,6,Bridges,Bridges allow diffusion of information between otherwise disconnected communities.,Local bridges bring otherwise distant communities together,“Bridge” concept provides an important piece of the micro = macro puzzle,What sort of relationships act as bridges?,7,Granovetter Transitivity,The stronger the tie between A and B, the larger the overlap in their relationship circles,Strong tie =,lots of time together = lots of opportunity for B to meet the As friends,similarity = greater chance that B will be “compatible” with As friends,physiological need for congruence = B will have a natural affinity for As friends, based on As opinion of them,8,Forbidden Triad,This triad will resolve to a fully connected triad,New edge need not be strong,Alternate: Any time strong tie A-B exists, then all of As strong ties will be at least weakly connected to B,Supported by evidence,9,All Bridges are Weak Ties!,Proof:,If A-B and A-C are strong, then forbidden triad implies that B-C is at least weak,If A-B is deleted, then A can still reach B via A-C-B,Small corner case: if both nodes have only a strong edge to each other, and no other strong edges, than it is a bridge,Unlikely in reality,All local bridges are also weak ties,Proof is identical,10,Implications,Removal of weak ties raises path lengths more than removal of strong ties,Assume: probability of info passing successfully between two nodes,is proportional to the number of paths connecting the two nodes,is inversely proportional to length of those paths,Conclusion: Removal of a weak edge damages the connectivity more than the removal of a strong edge,11,Evidence,Junior High Experiment: (Rapoport and Horvath, 1961),Student writes down an ordered list of 8 friend,Pick a random starting student,Breadth first search on 1st and 2nd friends,Count number of students seen after each cycle,Repeat using 3/4th, 5/6th, 7/8th,Largest number of people reached by using 7/8th, smallest using 1/2nd,12,Community Effects,13,Tipping Point,An individuals uptake of a new technique depends on how many of those around him have “bought in”,The “Tipping Point” (Gladwell, 2000),Quickly adopted techniques must be rapidly spread to many cliques,14,Tipping Point,People with many weak ties critical to spreading the idea,Example: Mass Hysteria in Textile Factory,Earliest people “infected” were:,friends with very few,acquaintances with many,Acted as “seeders”, rapidly disseminating idea to many friend circles at once,15,Community Co-ordination,Imagine a community organizing to defeat a common threat,Requires organization and leadership,Leadership requires trust in the leaders,Trust is difficult without a connection,16,Community Co-ordination,Without weak links, community exists as a set of strongly connected, but disjoint cliques,No one suitable to act as a leader for all,Example: Boston West End,Connections were mainly family-based,Few ways for weak links to be formed,17,Individual Effects,18,Access to Resources,Our weak ties are with people whose ties are with those socially distant to us.,Weak ties bring us knowledge of our community not available through friends,Many weak ties = more access to wider communitys ideas, resources, etc.,Few weak ties = little information of outside world,19,Access to Resources,Example: Academic Hiring,Schools reluctance to hire your own PhDs,Want to prevent “intellectual inbreeding”,20,Finding a Job,Do leads for new jobs come through strong or weak contacts?,Strong: More motivation to help you, since they know you better,Weak: Likely less overlap with leads you can easily get elsewhere,Study by author shows that weak wins,Most job referrals come through those who we see rarely: old school friends, former co-workers, etc.,21,22,Conclusions,Personal relationships (micro) bound to large-scale social structure (macro),Opposite to what you might expect:,Weak personal relationships bind communities together,Exclusively strong ties lead to global fragmentation,23,