Agent-Based Modeling and Simulation Agent-Based Modeling and Simulation of Collaborative Social Networks of Collaborative Social Networks Research in Progress Research in Progress Greg Madey Vincent Freeh Renee Tynan Computer Science Yongqin Gao Chris Hoffman North Carolina State Computer Science & Department of University Engineering Management University of Notre Dame University of Notre Dame AMCIS2003 Tampa, FL August 2003 Supported in part by the Supported in part by the National Science Foundation - Digital Society & Technology Program National Science Foundation - Digital Society & Technology Program
Outline Outline • Definitions: Agents, models, simulations, collaborative • Definitions: Agents, models, simulations, collaborative social networks, computer experiments social networks, computer experiments • Phenomenon: Free/Open Source Software (F/OSS) • Phenomenon: Free/Open Source Software (F/OSS) • Conceptual models • Conceptual models – ER model – ER model – BA model – BA model – BA model with constant fitness – BA model with constant fitness – BA model with dynamic fitness – BA model with dynamic fitness • Experiments and results • Experiments and results • Summary • Summary • Some discussion questions • Some discussion questions
Agent-Based Modeling and Agent-Based Modeling and Simulation Simulation • Conceptual models of a phenomenon • Conceptual models of a phenomenon • Simulations are computer implementations of the • Simulations are computer implementations of the conceptual models conceptual models • Agents in models and simulations are distinct • Agents in models and simulations are distinct entities (instantiated objects) entities (instantiated objects) – Tend to be simple, but with large numbers of them – Tend to be simple, but with large numbers of them (thousands, or more) - i.e., swarm intelligence (thousands, or more) - i.e., swarm intelligence – Contrasted with higher level “ intelligent agents ” – Contrasted with higher level “ intelligent agents ” • Foundations in complexity theory • Foundations in complexity theory – Self-organization – Self-organization – Emergence – Emergence
Collaborative Social Networks Collaborative Social Networks • • Research-paper co-authorship, small world phenomenon, e.g., Erdos Erdos Research-paper co-authorship, small world phenomenon, e.g., number ( number (Barabasi Barabasi 2001, Newman 2001) 2001, Newman 2001) • • Movie actors, small world phenomenon, e.g., Kevin Bacon number Movie actors, small world phenomenon, e.g., Kevin Bacon number (Watts 1999, 2003) (Watts 1999, 2003) • • Interlocking corporate directorships Interlocking corporate directorships • • Open-source software developers (Madey et al, AMCIS 2002) Open-source software developers (Madey et al, AMCIS 2002) • • Collaborators are nodes in a graph, and collaborative relationship are Collaborators are nodes in a graph, and collaborative relationship are the edges of the graph the edges of the graph
Classical Scientific Method Classical Scientific Method 1. Observe the world Observe the world 1. a) Identify a puzzling phenomenon Identify a puzzling phenomenon a) 2. Generate a falsifiable hypothesis Generate a falsifiable hypothesis (K. Popper) 2. (K. Popper) 3. Design and conduct an experiment with the Design and conduct an experiment with the 3. goal of disproving the hypothesis goal of disproving the hypothesis “ fails ” , then the hypothesis is a) If the experiment If the experiment “ fails ” , then the hypothesis is a) accepted (until replaced) accepted (until replaced) “ succeeds ” , then reject hypothesis, If the experiment “ succeeds ” b) If the experiment , then reject hypothesis, b) but additional insight into the phenomenon may be but additional insight into the phenomenon may be obtained and steps 2-3 repeated obtained and steps 2-3 repeated
The Computer Experiment The Computer Experiment
Agent-Based Simulation as Agent-Based Simulation as a Component of the a Component of the Scientific Method Scientific Method Modeling (Hypothesis) Agent -Based Observation Simulation (Experiment)
Agent-Based Simulation as Agent-Based Simulation as a Component of the a Component of the Scientific Method Scientific Method Modeling (Hypothesis) Social Network Model of F/OSS Agent -Based Observation Simulation (Experiment) Analysis of Grow Artificial SourceForge SourceForge Data
Open Source Software (OSS) Open Source Software (OSS) • … • Free … Free – – to view source to view source – – to modify to modify – to share – to share GNU – of cost – of cost Linux Savannah • • Examples Examples – – Apache Apache – – Perl Perl – – GNU GNU – – Linux Linux – – Sendmail Sendmail – – Python Python – – KDE KDE – – GNOME GNOME – – Mozilla Mozilla – – Thousands more Thousands more
Free Open Source Software (F/OSS) Free Open Source Software (F/OSS) • Development • Development – Mostly volunteer – Mostly volunteer – Global teams – Global teams – Virtual teams – Virtual teams – Self-organized - often peer-based meritocracy – Self-organized - often peer-based meritocracy – Self-managed - but often a “ charismatic ” leader – Self-managed - but often a “ charismatic ” leader – Often large numbers of developers, testers, support help, end – Often large numbers of developers, testers, support help, end user participation user participation – Rapid, frequent releases – Rapid, frequent releases – Mostly unpaid – Mostly unpaid
F/OSS F/OSS Developers Developers Larry Wall Perl Linus Tolvalds Richard Stallman Linux GNU GNU Manifesto Eric Raymond Cathedral and Bazaar
Puzzling Phenomenon F/OSS: A Puzzling Phenomenon F/OSS: A • • • Contradicts traditional • Research issues: Contradicts traditional Research issues: wisdom: wisdom: – Understanding motives – Understanding motives – Software engineering – Software engineering – Understanding processes – Understanding processes – Coordination, large numbers – Coordination, large numbers – Intellectual property – Intellectual property – Motivation of developers – Motivation of developers – Digital divide – Digital divide – Quality – Quality – Self-organization – Self-organization – Security – Security – Business strategy – Business strategy – Government policy – Government policy • • Almost everything is done Almost everything is done – Impact on innovation – Impact on innovation electronically and available in electronically and available in – Ethics – Ethics digital form digital form – Economic models – Economic models • • Opportunity for IS Research Opportunity for IS Research – Cultural issues – Cultural issues -- large amounts of online -- large amounts of online – International factors – International factors data available data available
SourceForge SourceForge • VA Software • Part of OSDN • Started 12/1999 • Collaboration tools • 58,685 Projects • 80,000 Developers • 590,00 Registered Users
Savannah Savannah • Uses SourceForge Software • Free Software Foundation •1,508 Projects •15,265 Registered Users
F/OSS: Importance Major Component of e-Technology Infrastructure with major presence in e-Commerce e-Science e-Government e-Learning Apache has over 65% market share of Internet Web servers Linux on over 7 million computers Most Internet e-mail runs on Sendmail Tens of thousands of quality products Part of product offerings of companies like IBM, Apple Apache in WebSphere, Linux on mainframe, FreeBSD in OSX Corporate employees participating on OSS projects
Free/Open Source Software Free/Open Source Software • Seems to challenge traditional economic assumptions • Seems to challenge traditional economic assumptions • Model for software engineering • Model for software engineering • New business strategies • New business strategies – Cooperation with competitors – Cooperation with competitors – Beyond trade associations, shared industry research, and – Beyond trade associations, shared industry research, and — shared product development! standards processes — shared product development! standards processes • Virtual, self-organizing and self-managing teams • Virtual, self-organizing and self-managing teams • Social issues, e.g., digital divide, international • Social issues, e.g., digital divide, international participation participation • Government policy issues, e.g., US software industry, • Government policy issues, e.g., US software industry, impact on innovation, security, intellectual property impact on innovation, security, intellectual property
Research Model Research Model Conceptual Explanatory Model of Parameter Values OSS: Agent-Based Modeling and Simulation Structural Features Understanding the Cross Validation Social and Task Combined Data Mining Dynamics that Predict Parameter Values Developer Behaviors Structural Features Social Network Analysis : Longitudinal Study of Preferential Parameter Values Attachment and Dynamic Attachment
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