Title
Modeling bursts and heavy tails in human dynamics.
Abstract
The dynamics of many social, technological and economic phenomena are driven by individual human actions, turning the quantitative understanding of human behavior into a central question of modern science. Current models of human dynamics, used from risk assessment to communications, assume that human actions are randomly distributed in time and thus well approximated by Poisson processes. Here we provide direct evidence that for five human activity patterns, such as email and letter based communications, web browsing, library visits and stock trading, the timing of individual human actions follow non-Poisson statistics, characterized by bursts of rapidly occurring events separated by long periods of inactivity. We show that the bursty nature of human behavior is a consequence of a decision based queuing process: when individuals execute tasks based on some perceived priority, the timing of the tasks will be heavy tailed, most tasks being rapidly executed, while a few experiencing very long waiting times. In contrast, priority blind execution is well approximated by uniform interevent statistics. We discuss two queuing models that capture human activity. The first model assumes that there are no limitations on the number of tasks an individual can hadle at any time, predicting that the waiting time of the individual tasks follow a heavy tailed distribution P(tau(w))similar to tau(-alpha)(w) with alpha=3/2. The second model imposes limitations on the queue length, resulting in a heavy tailed waiting time distribution characterized by alpha=1. We provide empirical evidence supporting the relevance of these two models to human activity patterns, showing that while emails, web browsing and library visitation display alpha=1, the surface mail based communication belongs to the alpha=3/2 universality class. Finally, we discuss possible extension of the proposed queuing models and outline some future challenges in exploring the statistical mechanics of human dynamics.
Year
DOI
Venue
2005
10.1103/PhysRevE.73.036127
PHYSICAL REVIEW E
Keywords
DocType
Volume
heavy tail,poisson process,stochastic process,web browsing,risk assessment,human behavior,heavy tailed distribution,probability theory,empirical evidence
Journal
73
Issue
ISSN
Citations 
3
1539-3755
68
PageRank 
References 
Authors
12.27
2
6
Name
Order
Citations
PageRank
Alexei Vázquez16812.27
João Gama Oliveira26812.27
Zoltán Dezsö36812.27
Kwang-Il Goh46812.27
Imre Kondor56812.60
Albert-lászló Barabási646491107.35