Don't just do something, stand there! Reflections on the counterintuitive behavior of complex systems, seen through the eyes of System Dynamics, Systems Thinking and simulation.
Long ago, in the MIT SD PhD seminar, a group of us replicated and critiqued a number of classic models. Some of those formed the basis for my model library. Around that time, Liz Keating wrote a nice summary of “How to Critique a Model.” That used to be on my web site in the … Continue reading “How to critique a model (and build a model that withstands critique)”
Via ScienceDaily, A large body of social science research has established that students tend to overestimate the amount of alcohol that their peers consume. This overestimation causes many to have misguided views about whether their own behaviour is normal and may contribute to the 1.8 million alcohol related deaths every year. Social norms interventions that … Continue reading “Dynamic Drinking”
Asmeret Naugle, Saeed Langarudi, Timothy Clancy propose to define System Dynamics in a new paper. The defining characteristics are: (1) models are based on causal feedback structure, (2) accumulations and delays are foundational, (3) models are equation-based, (4) concept of time is continuous, and (5) analysis focuses on feedback dynamics. I like the paper, but … Continue reading “What is SD?”
In a breakout in the student colloquium at ISDC 2022, we discussed the difficulty of getting a paper accepted into the conference, where the content was substantially a discrete event or agent simulation. Readers may know that I’m not automatically a fan of discrete models. Discrete time stinks. However, I think “discreteness” itself is not … Continue reading “Should System Dynamics Have a Big Tent or Narrow Focus?”
At ISDC 2018, we gave the Dana Meadows Award for best student paper to Gizem Aktas, for Modeling the Biological Mechanisms that Determine the Dynamics of Stress Response of the Human Body (with Yaman Barlas). This is a very interesting paper that elegantly synthesizes literature on stress, mood, and hormone interactions. I plan to write more about … Continue reading “Biological Dynamics of Stress Response”
This is the model library entry for my ISDC 2017 plenary paper with Larry Yeager on dynamic cohorts in Ventity: Dynamic cohorts: a new approach to managing detail While it is desirable to minimize the complexity of a model, some problems require the detailed representation of heterogeneous subgroups, where nonlinearities prevent aggregation or explicit chronological … Continue reading “Dynamic Cohorts”
I’m increasingly running into machine learning approaches to prediction in health care. A common application is identification of risks for (expensive) infections or readmission. The basic idea is to treat patients like a function approximation problem. The hospital compiles a big dataset on patient demographics, health status, exposure to procedures, and infection outcomes. A vendor … Continue reading “Prediction, in context”
I’m preparing for a talk on the dynamics of dictatorship or authoritarianism, which touches on many other topics, like polarization, conflict, terror and insurgency, and filter bubbles. I thought I’d share a few references, in the hope of attracting more. I’m primarily interested in mathematical models, or at least conceptual models that have clearly-articulated structure->behavior … Continue reading “Dynamics of Dictatorship”
There was lots of talk of dual process theory at the 2017 System Dynamics Conference. Nelson Repenning discussed it in his plenary presentation. The Donella Meadows Award paper investigated the effects on stock-flow task performance of priming subjects to think in System 2: The dual-process theory and understanding of stocks and flows Arash Baghaei Lakeh … Continue reading “System 3 thinking”