Coordination Event Detection and Initiator Identification in Time Series Data

Chainarong Amornbunchornvej,Ivan Brugere,Tanya Y Berger-Wolf,Damien R Farine,Ariana Strandburg-Peshkin,Margaret C Crofoot

doi:10.1145/3201406

Abstract

Behavior initiation is a form of leadership and is an important aspect of social organization that affects the processes of group formation, dynamics, and decision-making in human societies and other social animal species. In this work, we formalize the C oordination I nitiator I nference P roblem and propose a simple yet powerful framework for extracting periods of coordinated activity and determining individuals who initiated this coordination, based solely on the activity of individuals within a group during those periods. The proposed approach, given arbitrary individual time series, automatically (1) identifies times of coordinated group activity, (2) determines the identities of initiators of those activities, and (3) classifies the likely mechanism by which the group coordination occurred, all of which are novel computational tasks. We demonstrate our framework on both simulated and real-world data: trajectories tracking of animals as well as stock market data. Our method is competitive with existing global leadership inference methods but provides the first approaches for local leadership and coordination mechanism classification. Our results are consistent with ground-truthed biological data and the framework finds many known events in financial data which are not otherwise reflected in the aggregate NASDAQ index. Our method is easily generalizable to any coordinated time series data from interacting entities.

Highlights

Which zebra initiated the flight from a lion? Whom does the elephant herd follow to water? Who is the trend-setter whose opinion many follow at the moment? (And is it the same person whether it’s the opinion about the future of AI or the hottest lunch spot?) In all these scenarios, the initiator might not be the one who is speaking the loudest or positioned at the front of the group after the group has already agreed to follow (Dyer et al 2009; Stewart and Scott 1947)
The idea is that if we can use time series Y to significantly improve the prediction of the future activity of time series X, compared to using only the past information from X, Y Granger causes X
We demonstrate the performance of our framework by comparing with previous works on influence and leadership (Andersson et al 2008; Kempe et al 2003; Kjargaard et al 2013) as well as creating the Granger-causality framework based on the work by Liu et al (2012) to illustrate the potential of using Granger causality to infer leaders in time series

Summary

Introduction

Which zebra initiated the flight from a lion? Whom does the elephant herd follow to water? Who is the trend-setter whose opinion many follow at the moment? (And is it the same person whether it’s the opinion about the future of AI or the hottest lunch spot?) In all these scenarios, the initiator might not be the one who is speaking the loudest or positioned at the front of the group after the group has already agreed to follow (Dyer et al 2009; Stewart and Scott 1947). Who is the trend-setter whose opinion many follow at the moment? In order to identify those initiators or trend-setters, we must determine the moment of the group’s decision to follow. Coordination Initiator Inference Problem: An agreement of a group to follow a common purpose is manifested by its coalescence into a coordinated behavior. The process of initiating this behavior and the period of decision-making by the group members necessarily precedes the coordinated behavior. Given time series of group members’ behavior, the goal is to find these periods of decision-making and identify the initiating individual, if one exists. Initiating a group’s behavior is a form of leadership (Stueckle and Zinner 2008; Wilson 2009). Leadership is an important aspect of the social organization, formation, and decision-making of groups of people in online and offline communities, as well as other social animals. Many works defined leaders by their physical or behavioral characteristics rather than by observing processes of interaction (Northouse 2016)

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Conclusion