Food club simulation fits purchasing data with accuracy

Master’s student Antonio Jurlina has completed a simulation model of food buying clubs in which people share bulk purchases. Building on the work of Ethan Tremblay, Jurlina fit this model to data from 30 separate food clubs. The model simulates membership as a result of success in cooperative purchasing behavior between agents.

To simulate a club, the model takes a set of input variables: average catalog size, mean items per case, starting members, and the number of orders for a that club. It then creates a set of virtual agents who interact to share food purchases. Happy agents will help others. Unhappy agents will not help out. As a result simulated clubs have a cooperative momentum. This cooperative momentum determines whether members feel satisfied and stay in the club, or leave.

Membership of small food buying clubs over time. Data (red), Model (blue). Membership (y axis) over food club orders (x axis).

The model has two free parameters:

join_rate : the probability of additional members joining a club in a given order
prosociality : the average tendency of club members to be willing to buy something they don’t prefer to help another member

We fit the model to the data by finding the values of join_rate and prosociality that produce the closest membership trend line. These results show that our model can mimic real world clubs with good accuracy. Our next step will be to test the predictive capacity of the model by doing out of sample prediction tests.

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Proseminar on Evolution of Sustainability, University of Bern, Switzerland [video]

Video of Dr. Waring’s webinar for the University of Bern proseminar on the use of evolutionary social science for solving environmental dilemmas and evolving sustainable social-ecological systems. The Zoom recording is not of the highest quality, and it starts a little late.

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Are COVID-19 environmental improvements permanent?

During the coronavirus pandemic societies are re-thinking how they do things. Some of the changes also have environmental benefits. But will those benefits last?

I was interviewed in the Appalachian Mountain Club Outdoors Magazine on that question. Read it here.

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Pricing Nature Reduces Monetary Support for Conservation

Great work by my former student, and now assistant professor Sandra Goff shows that people will contribute LESS to conserving nature if they are told that nature has a price.

http://www.sciencedirect.com/science/article/pii/S0921800916313672

Implication: Don’t put a price tag on natural systems that need protection. Sandra is now an assistant professor at Skidmore College in New York.

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The Evolution of Co-operatives

Here is a nicely edited video of my recent MacPherson Lecture at the Canadian Centre for the Study of Cooperatives on “The Role of Cooperation in the Evolution of Co-operatives,” in which I attempt to highlight the role of cooperation in understanding organizational evolution.

Dr. Waring teaches at the University of Maine. Learn more: timwaring.info.

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