Intro to Agent Based Modeling at Strataconf 2013

transcript

Quantitative Insights from Qualitative Data

Presented by: Jacqueline Kazil@jackiekazil

October 28, 2013

Sunday, November 10, 13

Who am I? Sunday, November 10, 13

Overview of talk

• Introduction to agent-based models

• How are agent-based models built

• How/why/when to use you may want to use this approach

• What is ABM?

• History and sample

• Walk through of simple ABM

• How to get started

Overview

• Agent-based model

• Agent-based simulation

What is an ABM?

Agent-based modeling is a method of computational modeling that simulate interactions among agents with the purpose of viewing the effects on the system as a whole.

("Agent Based Modeling” 2013)

What is an ABM?ABM vs Classical Models

Classical: ‘...equations expressing relationships between observable components of a system...’

ABM: ‘...system-level patterns emerge from... interactions.’

(Koohafkan 2013)

A very brief history of ABM

Example Model...

Cholera Model Protypehttp://bit.ly/cholera-model

Walk through of an ABM

Context...

Race and Ethnicity 2010(By Eric Fischer)

(Fischer 2010)

Background...

Thomas Schelling on segregation

(Schelling 1974)

http://bit.ly/netlogo-segration

(Wilensky 1997, 1999)

Netlogo’s Segregation Model

(Wilensky 1997, 1999)

“This project models the behavior of two types of turtles in a mythical pond. The red turtles and green turtles get along with one another. But each turtle wants to make sure that it lives near some of "its own." That is, each red turtle wants to live near at least some red turtles, and each green turtle wants to live near at least some green turtles. The simulation shows how these individual preferences ripple through the pond, leading to large-scale patterns.”

How to get started

Agent-Based and Individual-Based

Modeling: A Practical Introduction

By Steven F. Railsback and Volker Grimm

(2011)

http://bit.ly/abm-practical

Growing Artificial Societies

By Joshua Epstein and Rob Axtell(1994)

Questions to ask

• What is the problem/question that I am trying to answer?

• What am I trying to measure?

• Do I have insight or literature that describes the behavior?

• What rules will the system have?

• What is important and what is not? (Start simple.)

• The Unthinkable: Who Survives When Disaster Strikes - and WhyBy Ripley, Amanda

• Five Days at Memorial: Life and Death in a Storm-Ravaged HospitalBy Sheri Fink

Sample qualitative data

Structure of the model

• What theory did you come up with to work off of?

• Who are the agents?

• What does the world look like? Is space important?

• What occurs in a time step?

• What is the order of action?

Map interactions

(Doncaster 2013)

Choose a language/toolkit

• Netlogo - http://ccl.northwestern.edu/netlogo/

• Mason - http://cs.gmu.edu/~eclab/projects/mason/

• Repast - http://repast.sourceforge.net/

• Repastpy - http://repast.sourceforge.net/repast_3/repastpy/

• More options and lots of info: http://www2.econ.iastate.edu/tesfatsi/acecode.htm

Build the model

Things to keep in mind

• Netlogo is great place to start

• Just because you built, doesn’t mean it’s right

• More doesn’t mean better

• Iterate, iterate, iterate (See Cholera model.)http://bit.ly/early-cholera

• Test and validate your results

Use the model. Report results.Rinse and repeat.

References"Agent Based Modeling.” Wikipedia, The Free Encyclopedia. Wikimedia Foundation, Inc. 17 September 2013. Web. 19 September 2013.

Crooks, Andrew. "Diseases and Refugee camps." GIS and Agent-Based Modelling: Diseases and Refugee camps. N.p., n.d. Web. 27 Oct. 2013. <http://www.gisagents.org/2012/05/diseases-and-refugee-camps.html>.

Doncaster, C. Patrick, Adam Jackson, and Richard A. Watson. “Competitive environments sustain costly altruism with negligible assortment of interactions.” Scientific Reports. 03 Oct. 2013. Article number: 2836. Nature Publishing Group. doi:10.1038/srep02836

Fischer, Eric. "Race and Ethnicity 2010." Flickr. Yahoo!, n.d. Web. 15 Oct. 2013. <http://www.flickr.com/photos/walkingsf/sets/72157626354149574/with/5559914315/>.

Koohafkan, Michael. "Fun with agent-based modeling." The research blog of Michael Koohafkan. N.p., n.d. Web. 10 Oct. 2013. <http://www.ocf.berkeley.edu/~mikeck/?p=282>.

Schelling, T.C. (1974) On the ecology of micromotives. The Corporate society. Marris, R. (ed). London: Macmillan: 19-64.

Stroud, Doug. [Photograph of a wheaten terrier]. (2013).

Stroud, Doug. [Photograph of a cane corso]. (2013).

Wilensky, U. (1997). NetLogo Segregation model. http://ccl.northwestern.edu/netlogo/models/Segregation. Center for Connected Learning and Computer-Based Modeling, Northwestern Institute on Complex Systems, Northwestern University, Evanston, IL.

Wilensky, U. (1999). NetLogo. http://ccl.northwestern.edu/netlogo/. Center for Connected Learning and Computer-Based Modeling, Northwestern Institute on Complex Systems, Northwestern University, Evanston, IL.

Questions?

jackiekazil@gmail.com@jackiekazil

Intro to Agent Based Modeling at Strataconf 2013

Technology