Sociology 204: Social Networks

Princeton University
Fall 2010
Monday and Wednesday: 10:00am-10:50am
Location: McCosh 28
Instructor: Matthew Salganik
Preceptors: Karen Levy and Lauren Senesac

This course provides students an introduction to the study of social networks. We will focus on understanding the causes and consequences of the patterns of relationships between individuals. Topics will include the small-world puzzle (six degrees of separation), the strength of weak ties, centrality, data collection, and the spread of diseases and fads.

Student grades will be based on the following:

In-class final exam: 45%
This in-class exam will cover the material from the entire semester. The exam will be Saturday, January 15th from 1:30pm to 4:30pm in McCosh 28.
Midterm exam: 25%
The date of the midterm exam will be Wednesday, October 27, 2010.
Homework/Precept: 30%
Each precept session will have an assignment that will serve as the the basis of the discussion. Some assignments will involve simple data collection and analysis, while others will involve writing assignments. Hard copies of these assignments will be due in class each Wednesday. If you cannot be in class on Wednesday, you can email your assignment to the leader of your precept, but they must receive it by 10am on Wednesday. If you do not turn in your assignment on time, you can still turn it in at your precept for a reduced grade (half credit). After your precept, you will not be able to submit your assignment unless you have a letter from the Dean of your college.

Numeric grades will be converted to letter grades at the end of the semester based on a standard scale.

There is one required text for the class: Six Degrees: The Science of a Connected Age by Duncan Watts. Other readings are available on the web or from blackboard. To understand the flow of ideas, students should do the readings for each lecture in the order that they are listed on the syllabus.

Course introduction (9/20/10)

No reading assigned.

The connected age and the small world problem (9/22/10)

Watts, Preface and Chapter 1.
Milgram, S. (1967). The small world problem. Psychology Today, 1:62-67 [Available from blackboard].
Travers, J. and Milgram, S. (1969). An experimental study of the small world problem. Sociometry, 32(4):425-443.
Kleinfeld, J.S. (2002). The small world problem. Society, 39(2):61-66 [Available from blackboard].

Understanding the small world phenomena (9/29/10)

Watts, Chapter 3.
Watts, D.J. (1999). Networks, dynamics, and the small world phenomenon. American Journal of Sociology, 105(2):493-527.
Beta model graph animation

Degree distributions and power laws (10/4/10)

Watts, Chapter 4, 101-114.
Barabasi, A.L. and Bonabeau, E. (2003) Scale-free networks. Scientific American, 50-59 [available from blackboard].
Barabasi, A.L. and Albert, R. (1999) The emergence of scaling in random networks. Science, 286:509-512.
Barabasi-Albert random graph animation
Liljeros, F. et al. (2001). The web of human sexual contacts. Nature, 411:907-908 with comment and rejoinder.

Affiliation networks/2-mode data (10/6/10)

Gladwell, M. (1999). Six degrees of Lois Weisberg. The New Yorker.
Watts, Chapter 4, 114-129.
Feld, S.L. (1981) The focused organization of social ties. American Journal of Sociology, 86(5):1015-1035.

Social search and the small world problem (10/11/10)

Watts, Chapter 5.
Kleinberg, J. (2000). Navigation in a small world. Nature, 406:845.
Watts, D.J., Dodds, P.S., and Newman, M.E.J. (2002). Identity and search in social networks. Science, 296:1302-1305.

Spread of disease in networks (10/13/10)

Watts, Chapter 6.
Klovdahl, A.S. (1985). Social networks and the spread of infectious disease: The AIDS example. Social Science and Medicine, 21(11):1203-1216.
Bearman, P.S., Moody, J.M., and Stovel, K. (2004). Chains of affection: The structure of adolescent romantic and sexual networks. American Journal of Sociology, 110(1):44-91.

The "madness" of crowds (10/18/10)

Watts, Chapter 7.
Asch, S.E. (1955). Opinions and social pressure. Scientific American, 193(5):31-35 [available on blackboard].
Bikhchandani, S. Hirshleifer, D. and Welch, O. (1998). Learning from the behavior of others: Conformity, fads, and informational cascades. Journal of Economic Perspectives, 12(3):151-170.
Tierney, J. (2007). Diet and fat: A severe case of mistaken consensus. New York Times.

Thresholds, cascades, and predictability (10/20/10)

Gladwell, M. (1996). The tipping point. The New Yorker.
Watts, Chapter 8.
Granovetter, M. (1978). Threshold models of collective behavior. American Journal of Sociology, 83(6):1420-1433.
Watts, D.J. (2002). A simple model of global cascades on random networks. PNAS, 99:5766-5771. (skim)

Cascades and fads in cultural markets (10/25/10)

Hedstrom, P. (2006). Experimental macro sociology: Predicting the next best seller. Science, 311:786-787.
Salganik, M.J., Dodds, P.S., and Watts, D.J. (2006). Experimental study of inequality and unpredictability in an artificial cultural market. Science, 311:854-856.
Salganik, M.J., and Watts, D.J. (2008). Leading the herd astray: Experimental study of self-fulfilling prophecies in an artificial cultural market. Social Psychology Quarterly, 71:338-355.

Midterm Exam (10/27/10)

Because of the midterm exam, there will be no precepts this week. After the exam we will have fall break.

Strength of weak ties (11/8/10)

Granovetter, M. (1973). The strength of weak ties. American Journal of Sociology, 78(6), 1360-1380.
Bian, Y. (1997). Bringing strong ties back in: Indirect ties, network bridges, and job searches in China. American Sociological Review, 62:366-385.

More strength of weak ties (11/10/10)

Centola, D. and Macy, M.W. (2007). Complex contagion and the weakness of long ties American Journal of Sociology, 113(3):702-734.
Centola, D. (2010). The spread of behavior in an online social network experiment Science, 329(5996):1194-1197.

Contagion of health behavior (11/15/10)

Thompson, C. (2009). Are Your Friends Making You Fat? New York Times Magazine, September 13, 2009.
Watch James Fowler on Colbert Report
Christakis, N.A. and Fowler, J.H. (2007). The Spread of Obesity in a Large Social Network over 32 Years New England Journal of Medicine, 357:370-379.
E. Cohen-Cole and J. M. Fletcher (2008). Detecting implausible social network effects in acne, height, and headaches: longitudinal analysis British Medical Journal, 337.

Experimental studies of contagion (11/17/10)

Nickerson, D.W. (2008). Is voting contagious? Evidence from two field experiments. American Political Science Review, 102(1):49-57.
Sacerdote, B. (2001). Peer Effects with Random Assignment: Results for Dartmouth Roommates. Quarterly Journal of Economics 116(2):681-704.

Friends of friends (11/22/10)

Feld, S. (1981). Why your friends have more friends than you. American Journal of Sociology, 96(6):1464-1477.
Christakis, N.A. (2010). How social networks predict epidemics. TED Talk.
Christakis, N.A. and Fowler, J.H. (2010). Social network sensors for early detection of contagious outbreaks. PLoS ONE 5(9): e12948.

Sampling, social networks, and hidden populations most at-risk for HIV/AIDS (11/24/10)

Salganik, M.J. and Heckathorn, D.D. (2004). Sampling and estimation in hidden populations using respondent-driven sampling. Sociological Methodology, 34:193-239.
Bernard, H.R. et al. (2010). Counting hard-to-count populations: The network scale-up method for public health. Sexually Transmitted Infections. [available from blackboard].
There will be no precepts this week because of Thanksgiving.

Homophily (11/29/10)

McPherson, M, Smith-Lovin, L., and Cook, J.M. (2001). Birds of a feather: Homophily in social networks. Annual Review of Sociology, 27:415-444.
Segal, M.W. (1974). Alphabet and attraction: An unobtrusive measure of the effect of propinquity in a field setting. Journal of Personality and Social Psychology, 30(5):654-657.
Kossinets, G. and Watts, D.J. (2009). Origins of Homophily in an Evolving Social Network. American Journal of Sociology, 115(2)405-450.

Friendship formation (12/01/10)

Small, M.L. (2010). Unanticipated Gains: Origins of Network Inequality in Everyday Life: Chapters 1-3 (pages 3-83) [available from blackboard].
Uzzi, B. and Dunlap, S. (2005) How to build your network Harvard Business Review, 83(12):53-60.

Core discussion networks (12/6/10)

Fountain, H. (2006). The Lonely American Just Got a Bit Lonelier. The New York Times, July 2.
McPherson, M., Smith-Lovin, L., and Brashears, M.E. (2006). Social Isolation in America: Changes in Core Discussion Networks over Two Decades. American Sociological Review, 71(3):353-375.
Fischer, C. (2009). The 2004 GSS Finding of Shrunken Social Networks: An Artifact? American Sociological Review, 74(4):657-669.
McPherson, M., Smith-Lovin, L., and Brashears, M.E. (2009). Models and Marginals: Using Survey Evidence to Study Social Networks. American Sociological Review, 74(4):670-681.

Structural holes, closure, and social capital (12/8/10)

Coleman, J.S. (1988). Social capital in the creation of human capital. American Journal of Sociology, 94:S95-S120.
Burt, R.S. (2004). Structural holes and good ideas. American Journal of Sociology, 110(2):349-399.

Digital traces of communication: mobile phones (12/13/10)

Onnela, J.P. et al. (2008). Structure and tie strengths in mobile communications networks. PNAS, 104(18):7332-7336.
N. Eagle, A. Pentland, and D. Lazer (2009). Inferring social network structure using mobile phone data. PNAS, 106(36):15274-15278. with Comment and Reply.

Digital traces of communication: Facebook and Twitter (12/15/10)

Bakshy, E., Hofman, J.M., Mason, W.A., Watts, D.J. (2011) Everyone's an Influencer: Quantifying Influence on Twitter, Fourth International Conference on Web Search and Data Mining.
Wimmer, A. and Lewis, K. (2010). Beyond and below racial homophily. ERG models of a friendship network documented on Facebook, American Journal of Sociology, in press.