SOCIAL LEARNING (Ec 717)

Slides 1 (Introduction - quadratic model)

Slides 2 (Cascades and Herds)

NOTES
  • Chapters 1-6: Bayesian learning, Vives model, cascades, herds, delay (to be edited)
  • Bikhchandani, Sushil, David Hirshleifer, Omer Tamuz, Ivo Welch (2024) "Information Cascades and Social Learning," Journa of Economic Literature, 62(3), 1040-93. 
    • The paper is disappointing, but perhaps, something can be extracted from it.

02/02:

For 02/04:

Homework 
In the posted notes (Chapters 1-6),
  • Exercises 1.1, 1.3, 1;4
  • Exercise 3.2, questions 1 and 2, question 3 where the cost is a linear function of the precision and c(0)=0; question 4 optional.
  • Exercise 4.6. 

Preparation:

  1. Do the problem on delays that was sent to your by e-mail.
  2. Read carefully the introduction to the Chapter 5, which was distributed in class (the same as the chapter in the notes posted above.
  3. Read the introduction of the following paper (and have a peek at the rest of the paper)
  4. Have a look at the rest of Chapter 5 (notes).

Week of 02/09:

  • 02/09: social learning through words.
The pbs 2 and 3 should be tacked only afteer the problem on global games. That problem should be done before the next class (this Wednesday). I know, it's little time, but you will gain more from the class. If you are short of time, don't do question 6. (1-5 do not require algebra).
  • Problem on global games
    • This is a ``problem for learning'': Do not turn an answer in class. But you may (are encouraged) to write one for yourself.
  • Problem 2

For 02/27 

  • Slides (UPDATED) on Benabou, R. (2013). “Groupthink: Collective Delusions in Organizations and Markets,” The Review of Economic Studies, 80(2), 429-462.

March 2-4: last papers:

  • Avery, C an P. Zemsky (1998)."Multidimensional Uncertainty and Herd Behavior in Financial Markets," AER, 88(4), 724-748.
  • Benabou, R. and N. Vellodi (2025). ``(Pro-)Social Learning an Strategic Disclosure,'' American Economic Journal: Microeconomics, 17(4), 102-125.
  • Smirnov, A. and E. Starkov (2025). ``Designing Social Learning," European Economic Review, 178.
  • Orzach, Roi (2016). "Conformity Concerns: A Dynamic Perspective," WP.
  • Dixit, A. and J. Weibull (2007). "Political polarization," PNAS, 104(18), 7351-7356.
  • Levy, G. and R. Razin (2025). "Political Social Learning: Short-Term Memory and Cycles of Polarization," AER, 115(2), 635-659.