The Local Food Economy Game - You are what you eat!

Use Case Observations from Grinnell Farmers' Market

Jelal Younes — Fri, 11 Aug 2006 16:39:17 -0400

From my visit to the Grinnell farmersâ€™ market on August 11, 2006, I designed both a template for interactions between vendors and customers, and a set of use cases depicting these interactions.

In all interactions between vendors and buyers, there are two constants: the customer walking over to the stand, and the customer leaving the stand. After these obvious aspects of the interaction, there are three variables in any vendor-customer interaction: amount of time spent speaking with the vendor, amount of time spent examining the goods on offer, and the amount of goods ultimately bought by the customer. A fourth variable would be the topics discussed by the vendor and customer (where the goods were grown/made, how much they cost, etc.); unfortunately, my position as an observer did not allow me to watch the interactions closely enough to observe interactions in such detail.

Interaction between buyer and seller at Farmers' Market

Jelal Younes — Mon, 07 Aug 2006 17:22:57 -0400

I have been trying to figure out the Metamodel presented by Jim yesterday on this website. I have tried to work through a simple model of an interaction between a buyer and seller at a farmers' market; it is shown below in the attached document. I am certain that this is not precisely how the interaction would be represented in our ABM program; any thoughts on how it should be altered? I want to make sure I have a simple interaction down before I move on to modeling larger environments, such as the entire farmers' market.

LFEGame Model - The Logical View Introduction

Sohodojo Jim — Sun, 06 Aug 2006 18:08:17 -0400

Click to view The LFEGame Model - Logical ViewWelcome to the Introduction to the first mini-book, Local Food Economy Game - Logical View, in the Local Food Economy Game Model Repository. This model will guide and constrain our design and implementation of the LFEGame.com agent-based simulation model.

This general class model is more accurately described as a metamodel. A metamodel is a model used to build other models. That is, it is a model that prescribes how to specify models that comply with its general architecture and constraints on the relationships between allowable model elements. "Allowable" in this sense means that the element is somehow derived from and related to an element in the metamodel.

A metamodel can be used two ways. It may be used ro guide development of new models built "from scratch" as solutions to a problem or design need. Or it can be used as a specification to guide the selection of technology candidates to be used in implementation of the proposed solution. We will, for example, take each of the agent-based simulation technology platforms that Jelal has identified through his web research and assess its features and capabilities in light of its ability to express models that satisfy our metamodel.

LocalHarvest

Jelal Younes — Fri, 04 Aug 2006 17:42:53 -0400

"The freshest, healthiest, most flavorful organic food is what's grown closest to you. Use our website to find farmers' markets, family farms, and other sources of sustainably grown food in your area, where you can buy produce, grass-fed meats, and many other goodies. If you are a farmer, market manager, or run a business related to locally-grown food, you can add your listing to our directory - free."

At LocalHarvest.org, you can search for online stores, farms, community supported agriculture (CSA), farmers' markets, restaurants, g

"Forecasting Consumer Price Indexes for Food"

Jelal Younes — Fri, 04 Aug 2006 17:21:55 -0400

Located here is an article entitled â€œForecasting Consumer Price Indexes for Food: A Demand Model Approach,â€ by Kuo S. Huang. Huang uses an inverse demand function to assess the change in quantity demanded for a variety of goods (including beef, eggs, fruits, vegetables, cerealâ€¦) based on a one percent change in price of that good. Huang presents a chart that shows, for example, that a one percent increase in the price of poultry would result in a .84 percent decrease in the quantity demanded of poultry. He also gives figures for cross elasticity of demand: A one percent increase in the price of red meat, for example, .91 percent decrease in the quantity demanded of beef.

More on NetLogo

Jelal Younes — Fri, 04 Aug 2006 16:59:25 -0400

Having downloaded NetLogo and played around with it for a while, I am unsure whether it will meet the needs of our modeling project.

NetLogo is particularly aimed at modeling systems as they adapt over time. Agents in NetLogo continuously respond to each otherâ€™s decisions, resulting in an ever-changing environment. To a great extent, we are interested in modeling a system that will develop over time: at a farmersâ€™ market, for example, a seller makes a decision (setting up a vendor station), a buyer makes a decision motivated by the sellerâ€™s decision (walking over to the vendor station), then another decision (whether or not to buy from the this particular vendor), etc. For these types of interactions, it is crucial to have a simulation program that effectively displays change over time in the system, showing how decisions by each agent impacts each following decision by other agents.

Directory of agent-based modeling links

Jelal Younes — Thu, 03 Aug 2006 16:08:53 -0400

Located here is a directory of links to applications of agent-based modeling, arranged by subject area. Of greatest importance to us is the economics section, which includes such projects as "artificial life simulation of the textile/apparel market," and "agent based simulation of the hotelling game." The page is put together by Craig Reynolds.

A simple introduction to agent-based modeling

Jelal Younes — Thu, 03 Aug 2006 15:43:22 -0400

For those who are unfamiliar with agent-based modeling (ABM), here is an easy-to-understand introduction to the subject. It is a list of answers to frequently asked questions about ABM, entitled "Agent-based modeling of complex, adaptive systems." It explains how agent-based modeling allows these systems to be modeled, and why modeling is a useful tool for understanding these systems.

Some articles on agent-based simulation

Jelal Younes — Thu, 03 Aug 2006 15:35:21 -0400

Just to update on some of the work I've been doing, here and here are links to a couple articles I've read about agent-based simulation that I did not find worthy of individual write-ups as they are not particularly useful to our project. The first article, by Robert Axelrod, presents a walk-through for those who plan to begin an agent-based simulation project, but does not really advance any new ideas for us.

"The World is Flat"

Jelal Younes — Wed, 02 Aug 2006 16:34:59 -0400