Tag Archives | Unpredictability

Threshold Models of Collective Behavior II: The Predictability Paradox and Spontaneous Instigation

Michael W. Macy, Anna Evtushenko

Sociological Science December 8, 2020
10.15195/v7.a26


Collective behavior can be notoriously hard to predict. We revisited a possible explanation suggested by Granovetter’s classic threshold model: collective behavior can unexpectedly fail, despite a group’s strong interest in the outcome, because of the sensitivity of cascades to small random perturbations in group composition and the distribution of thresholds. Paradoxically, we found that a small amount of randomness in individual behavior can make collective behavior less sensitive to these perturbations and therefore more predictable. We also examined conditions in which collective behavior unexpectedly succeeds despite the group’s weak interest in the outcome. In groups with an otherwise intractable start-up problem, individual randomness can lead to spontaneous instigation, making outcomes more sensitive to the strength of collective interests and therefore more predictable. These effects of chance behavior become much more pronounced as group size increases. Although randomness is often assumed to be a theoretically unimportant residual category, our findings point to the need to bring individual idiosyncrasy back into the study of collective behavior.
Creative Commons LicenseThis work is licensed under a Creative Commons Attribution 4.0 International License.

Michael W. Macy: Department of Sociology and Department of Information Science, Cornell University
E-mail: mwm14@cornell.edu

Anna Evtushenko: Department of Information Science, Cornell University
E-mail: ae392@cornell.edu

Acknowledgments: We thank Jon Kleinberg, Dana Warmsley, and Danielle Toupo for contributing ideas and technical suggestions. This research was supported by the National Science Foundation (SES 1756822, “Testing Unpredictability with MultipleWorlds”). Correspondence should be sent to Michael W. Macy, Department of Sociology, Cornell University, Ithaca, NY 14853.

  • Citation: Macy, Michael W., and Anna Evtushenko. 2020. “Threshold Models of Collective Behavior II: The Predictability Paradox and Spontaneous Instigation.” Sociological Science 7: 628-648.
  • Received: October 18, 2020
  • Accepted: November 1, 2020
  • Editors: Jesper Sørensen, Olav Sorenson
  • DOI: 10.15195/v7.a26


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When Forecasts Fail: Unpredictability in Israeli-Palestinian Interaction

Charles Kurzman, Aseem Hasnain

Sociological Science, June 23, 2014
DOI 10.15195/v1.a16

This article explores the paradox that forecasts may be most likely to fail during dramatic moments of historic change that social scientists are most eager to predict. It distinguishes among four types of shocks that can undermine the predictive power of time series analyses: effect shocks that change the size of the causal effect; input shocks that change the causal variables; duration shocks that change how long a causal effect lasts; and actor shocks that change the number of agents in the system. The significance of these shocks is illustrated in Israeli–Palestinian interactions, one of the contemporary world’s most intensely scrutinized episodes, using vector autogression analyses of more than 15,000 Reuters news stories over the past three decades. The intervention of these shocks raises the prospect that some historic episodes may be unpredictable, even retrospectively.

Charles Kurzman: Department of Sociology, University of North Carolina at Chapel Hill. E-mail: kurzman@unc.edu

Aseem Hasnain: Department of Sociology, University of North Carolina at Chapel Hill. E-mail: ahasnain@unc.edu

  • Citation:Kurzman, Charles and Aseem Hasnain. 2014. “When Forecasts Fail: Unpredictability in Israeli-Palestinian Interaction.” Sociological Science 1: 239-259.
  • Received: March 7, 2014
  • Accepted: April 23, 2014
  • Editors: Jesper Sørensen, Delia Baldassarri
  • DOI: 10.15195/v1.a16

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