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Strength of Weak Ties (Granovetter)
What is a weak tie? <ul><li>Strength of tie as a linear combination </li></ul><ul><ul><li>F =  Frequency of Contact </li><...
Simplification <ul><li>For purpose of building theory, ties classified as  </li></ul><ul><ul><li>“ strong” </li></ul></ul>...
Example A B S={C,D,E…}
Connection Closure <ul><li>If  </li></ul><ul><ul><li>A is connected to B (strong tie) </li></ul></ul><ul><ul><li>A is conn...
Cognitive Balance <ul><li>Anything short of a positive tie between B and C “would induce psychological strain”  </li></ul>
The “Forbidden Triad” <ul><li>The amount of dissonance between B and C is proportional to strength of ties A-B and A-C </l...
Connections and Similarity <ul><li>Newcomb(1961), Friedkin (later) </li></ul><ul><ul><li>The stronger the tie connecting t...
Weak ties and Bridging <ul><li>Strong ties are unlikely to be bridges </li></ul><ul><li>Weak ties can bridge distinct grou...
 
 
Local Bridges <ul><li>Global bridges (I.e. cutpoints) are unlikely in real networks </li></ul><ul><ul><li>Single ties betw...
Diffusion <ul><li>Weak ties speed up information diffusion </li></ul><ul><ul><li>Shorter distances mean faster penetration...
Weak Ties in Ego Nets <ul><li>Burt: look at overall density and redundancy in ego nets (I.e.  Structural holes) </li></ul>...
Empirical Study <ul><li>Job search in Boston </li></ul><ul><ul><li>Survey asks how applicant found out about the job openi...
Hypothesis: <ul><ul><li>These with strong ties to  ego  are more motivated to help find a job </li></ul></ul><ul><ul><li>W...
Result <ul><li>16.7% report strong ties (interact often) </li></ul><ul><li>55.6% report mid-strength (occasionally) </li><...
Questions <ul><li>Are these gradations sufficient? </li></ul><ul><ul><li>Do we need greater granularity? </li></ul></ul>
Questions <ul><li>What is possible distribution of overall tie strength in the network?  </li></ul><ul><ul><li>Skewed norm...
More results <ul><li>Source of job information: </li></ul><ul><ul><li>39.1%: direct from employer </li></ul></ul><ul><ul><...
Leadership and weak ties <ul><li>High number of strong ties in the in-group generally means less ties to the out-group </l...
Weak ties in politics <ul><li>Trust in a leader a function of having a bridging tie from ego to leader  </li></ul><ul><ul>...
Weak ties in politics <ul><li>Politicians must cultivate weak ties near election time </li></ul><ul><ul><li>“ kissing babi...
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10 Strength Of Weak Ties

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10 Strength Of Weak Ties

  1. 1. Strength of Weak Ties (Granovetter)
  2. 2. What is a weak tie? <ul><li>Strength of tie as a linear combination </li></ul><ul><ul><li>F = Frequency of Contact </li></ul></ul><ul><ul><li>E = Emotional intensity </li></ul></ul><ul><ul><li>I = Intimacy (mutual confiding) </li></ul></ul><ul><ul><li>R = Reciprocal services </li></ul></ul><ul><ul><li>l ij =w 1 F+w 2 E+ w 3 I+ w 4 R </li></ul></ul><ul><ul><li>Granovetter leaves exact functional form and weighting “postponed for future empirical work” </li></ul></ul>
  3. 3. Simplification <ul><li>For purpose of building theory, ties classified as </li></ul><ul><ul><li>“ strong” </li></ul></ul><ul><ul><li>“ weak” </li></ul></ul><ul><ul><li>“ absent” </li></ul></ul>
  4. 4. Example A B S={C,D,E…}
  5. 5. Connection Closure <ul><li>If </li></ul><ul><ul><li>A is connected to B (strong tie) </li></ul></ul><ul><ul><li>A is connected to C (strong tie) </li></ul></ul><ul><ul><li>A-B and A-C are independent </li></ul></ul><ul><li>Then </li></ul><ul><ul><li>P(B-C | A-B, A-C) = P(A-B)*P(A-C) </li></ul></ul><ul><ul><li>A weaker connection B-C exists with a higher probability </li></ul></ul><ul><ul><li>Common strong ties generate new connections </li></ul></ul>
  6. 6. Cognitive Balance <ul><li>Anything short of a positive tie between B and C “would induce psychological strain” </li></ul>
  7. 7. The “Forbidden Triad” <ul><li>The amount of dissonance between B and C is proportional to strength of ties A-B and A-C </li></ul><ul><li>If A-B and A-C are strong, triad occurs rarely </li></ul><ul><li>If A-B and A-C are weak, dissonance is low and weak tie B-C can be present </li></ul>A B C Dissonance
  8. 8. Connections and Similarity <ul><li>Newcomb(1961), Friedkin (later) </li></ul><ul><ul><li>The stronger the tie connecting two individuals, the more similar these individuals are </li></ul></ul><ul><ul><li>Thus, if A-B and A-C are strong ties </li></ul></ul><ul><ul><ul><li>B is similar to A, C is similar to A </li></ul></ul></ul><ul><ul><ul><ul><li>By transitivity </li></ul></ul></ul></ul><ul><ul><ul><li>B is similar to C </li></ul></ul></ul>
  9. 9. Weak ties and Bridging <ul><li>Strong ties are unlikely to be bridges </li></ul><ul><li>Weak ties can bridge distinct groups without interpersonal dissonance </li></ul>
  10. 12. Local Bridges <ul><li>Global bridges (I.e. cutpoints) are unlikely in real networks </li></ul><ul><ul><li>Single ties between “clumps” are unlikely </li></ul></ul><ul><li>Local bridges create paths between groups </li></ul><ul><ul><li>Local bridge of degree n </li></ul></ul><ul><ul><li>Weak ties allow for more redundancy </li></ul></ul><ul><ul><li>Shorter paths </li></ul></ul>
  11. 13. Diffusion <ul><li>Weak ties speed up information diffusion </li></ul><ul><ul><li>Shorter distances mean faster penetration </li></ul></ul><ul><ul><li>More redundancy means wider reach </li></ul></ul>
  12. 14. Weak Ties in Ego Nets <ul><li>Burt: look at overall density and redundancy in ego nets (I.e. Structural holes) </li></ul><ul><li>Granovetter: Partition the ego network into three groups: </li></ul><ul><ul><li>Strong ties </li></ul></ul><ul><ul><li>Weak ties </li></ul></ul><ul><ul><ul><li>Personal ties of the Ego </li></ul></ul></ul><ul><ul><li>Bridging weak ties </li></ul></ul><ul><ul><ul><li>Guaranteed to connect ego to outside groups </li></ul></ul></ul>
  13. 15. Empirical Study <ul><li>Job search in Boston </li></ul><ul><ul><li>Survey asks how applicant found out about the job opening </li></ul></ul><ul><ul><li>If job is found through personal contacts: </li></ul></ul><ul><ul><ul><li>How often does ego see the contact? </li></ul></ul></ul><ul><ul><ul><li>Where did the contact get the information? </li></ul></ul></ul>
  14. 16. Hypothesis: <ul><ul><li>These with strong ties to ego are more motivated to help find a job </li></ul></ul><ul><ul><li>Weak ties connect to information outside immediate group </li></ul></ul><ul><ul><li>Information gets diffused by long paths </li></ul></ul>
  15. 17. Result <ul><li>16.7% report strong ties (interact often) </li></ul><ul><li>55.6% report mid-strength (occasionally) </li></ul><ul><li>27.8% interact rarely </li></ul><ul><li>Often > twice a week </li></ul><ul><li>Occasionally > once a year </li></ul><ul><li>Rarely < once a year </li></ul>
  16. 18. Questions <ul><li>Are these gradations sufficient? </li></ul><ul><ul><li>Do we need greater granularity? </li></ul></ul>
  17. 19. Questions <ul><li>What is possible distribution of overall tie strength in the network? </li></ul><ul><ul><li>Skewed normal? </li></ul></ul><ul><ul><li>Maybe a power law? </li></ul></ul><ul><ul><ul><li>We know that degree distributions tend to power laws </li></ul></ul></ul><ul><ul><li>Does it affect what ties have higher probability of being used for job search? </li></ul></ul>
  18. 20. More results <ul><li>Source of job information: </li></ul><ul><ul><li>39.1%: direct from employer </li></ul></ul><ul><ul><li>45.3%: one intermediary </li></ul></ul><ul><ul><li>12.5%: two </li></ul></ul><ul><ul><li>3.1%: > 2 </li></ul></ul>
  19. 21. Leadership and weak ties <ul><li>High number of strong ties in the in-group generally means less ties to the out-group </li></ul><ul><ul><li>Related to limited cognitive capacity? </li></ul></ul><ul><li>Societies characterized by tight in-groups emerge local leaders, but each in-group acts on its own </li></ul>
  20. 22. Weak ties in politics <ul><li>Trust in a leader a function of having a bridging tie from ego to leader </li></ul><ul><ul><li>(even a very weak one) </li></ul></ul>
  21. 23. Weak ties in politics <ul><li>Politicians must cultivate weak ties near election time </li></ul><ul><ul><li>“ kissing babies” </li></ul></ul><ul><ul><li>Name recognition </li></ul></ul><ul><li>Strong ties are required to get things done </li></ul><ul><ul><li>Committee work </li></ul></ul>

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