System Dynamics, Agent-Based and Discrete-Event simulations are three competing and complementary simulation methods that are used to address a wide range of real-world problems. Each one of these has its pros and cons and can be applied better or worse depending on the context of the problem but can also be complementary in order to capture different pieces of the reality we want to simulate.

As System Dynamics seems to be an obscure topic for most discrete-event and agent-based modelers, the opposite is also true. And assuming good practices are in place, contrary to Agent-Based modeling guidelines, in System Dynamics, there is no standardized way in which a section of a model can be reutilized and the definition of what a sub-model or module is, depends largely on the context of the modeler. In other words, while in Agent-Based modeling, the sub-model is the agent itself, in System Dynamics, the sub-model can be a theme, an entity, a set of stocks that look good together, the importance of a sub-system, etc. A solution to this standard modularization problem, both in its qualitative and quantitative forms was discussed during this conference, in particular for Work-in-Progress sessions.

From a qualitative point of view, the presentation “Modelling the Complexity of Large Systems: A Network-aided System Dynamics Approach”, intends to use a method based on graph theory to identify themes within a complex network of causal relationships. Each theme can be approached separately by the subject matter expert that is associated with that theme, while also helping define boundaries for future work to be developed (see Figure 1). This is a great approach because it highlights the themes and transforms eventually this complicated network into a well-designed Causal Loop Diagram, with clear sections that are easy to read and understand. Looking at these themes, to a multi-method simulations developer, it appears that these themes are very closely related to the concept of an agent.

Figure 1: Social network of themes and causal loop diagram of selected themes
(Wang, Zimmermann: Modelling the Complexity of Large Systems: A Network-aided System Dynamics Approach, 2022 International System Dynamics Conference, figure used with permission.)

From a quantitative perspective, in their workshop “Using a Tool to Professionalize Model development” Copernicos showed a tool that attempts to improve the structure of a model by creating entities that represent certain hidden topics in models, mostly looking at dimensions and subscripts (or arrays), and generating modules in Stella or sub-models in Vensim that represent what they call hidden topics. This is done with an Excel plugin that acts as a transformation interface that reads the model and generates a new model that is organized with the concept of entities. The arrays are still there as defined by the modeler, but the way the model is organized in modules (in Stella) or sub-models (in Vensim) becomes very similar to what an agent would be in agent-based modeling or to what an entity would be in Ventity. In my opinion, this is a great approach since it goes in the direction of standardizing the modularization of a big complex model, which is the topic we are discussing in this article.

In the multi-method framework, mostly used by AnyLogic developers, it is common to solve these problems by having Agent-Based/System-Dynamics hybrids, in which modules or arrays are replaced by the concept of agent. From the qualitative side, having agents as part of the conceptual framework greatly helps build a hierarchical network of reusable modules that represent the system that needs to be conceptualized. From the quantitative side, Copernicos’ attempt to generate entities is a great idea to build a standardized model structure, which is what multi-method modelers like me do use the standard multi-method framework present in Software such as AnyLogic.

During the conference, work related to hybrid simulations was sparse, and of course, this is a System Dynamics conference, so it’s maybe expected, but it seems to me from conversations with people during the event, that the interest in relation to multi-method modeling is much higher than what the presented work shows. The presenter of “A Cross-Disciplinary Computational Framework for Hybrid Simulation and Modeling” reported on a systematic literature review on how hybrid modeling has increased in popularity. Only a few authors presented hybrid models, e.g. Portia Mupfumira showed hybrid agent-based/System-Dynamics models in two presentations: “Smart Cities Hybrid Conceptual Modelling” and “Development of Hybrid Smart Energy Distribution Decision Support Model: Case of Zimbabwe” and Al Thibeault used Ventity to present “Agent-based Model for Testing Policy Options for Long-term Stability and Sustainability in the Rare Earth Mineral Sector”. Also, the Software Modelica’s object-oriented and multi-method capabilities were presented in the poster “Hierarchical, Component-Based Modeling Using the Cyber-Physical Modeling Language Modelica”.

During the roundtable “Panel on Careers in System Dynamics”, one of the panel members, with 20 years of experience in the field, talked about Agent-Based as a sexy methodology. And this is true, in particular, because agent-based is significantly more used in the business world (along with discrete events), making it very useful to build a proof of concept models very fast with 2D and 3D animations that can be very beautiful and attractive. But he talked about Agent Based modeling as something that has nothing to do with System Dynamics, expressing a separation when it comes to comparing both methods, instead of a synergy. The panel also talked about the struggle to be taken seriously as a System Dynamics professional and the struggle to get stakeholders to buy into the System Dynamics concepts but isn’t maybe the multi-method idea, that is largely documented in the literature the first step toward a thriving System Dynamics community? I think it might be.

We cannot all succeed when (more than) half of us are held back.

This slightly modified quote is from Malala Yousafzai, the courageous young woman who stood up for her right to be educated. It summarizes the ethos of presentations at the International Systems Dynamics Conference held in Frankfurt and online in July 2022 which focused on improving diversity within organizations. Systems Dynamics modeling is being used in various ways to understand the mechanisms by which more than half of the world’s populations are being held back, and to support evidence-based solutions for change.

In the first plenary, Jeroen Struben presented a model to explain why women chess players drop out of competitions in their late twenties, never to return. The data from the Netherlands showed that the presence of peers and role models, and the culture of the broader community were major explanatory factors. There is also a project that will look at women chess players with and without children, which is already finding that family caring commitments have a large impact on women’s decisions.

Suzanne Manning (disclaimer: that’s me) also highlighted the impact of caring responsibilities on women, on career progression in a social science research team. In a qualitative model of mechanisms that were holding women back, factors such as family commitments and expertise in ‘softer’ science disciplines like sociology and indigenous knowledge (compared to expertise in more quantitative systems dynamics), were partially career-limiting.

The model of Inge Bleijenberg looked at mechanisms to explain why ‘ingroups’ of white, upper-class men hold a pay advantage over ‘outgroups’ (everyone else) in academia. Her model showed that while the human capital of both groups was quite similar, the ingroups made more and higher wage claims which were more likely to be accepted. This model shows how structural bias is built into our systems.

Several presentations addressed systemic bias, with models that were used as heuristic tools for organizations to make changes to increase staff diversity. A common theme was that organizations needed to be shown the things that were within their control and to realize that business-as-usual was not good enough to make a difference. Systems Dynamics models were key for getting organizations to make these mental shifts. Amin Dehdarian from EDGE had a process for gender targets set within a framework of representation, pay equity, policies and practices, and organizational culture. Systems Dynamics models were used to show how effective the strategies could be. A similar approach was taken by Hugo Herrera, who used microworld simulation models to help organizations develop a coherent suite of strategies for decreasing their gender pay gaps. Ivan Taylor, Takuma Ono, and Saraj Koul presented their case study of a model for increasing diversity in organizations applied to Twitter that have a vision of 25% of their US staff being from disadvantaged groups by 2025. Like the other models mentioned in this post, their data shows that improving fairness and diversity in recruitment and promotion are key aspects for improving diversity in the organization. They do acknowledge that their model does not currently account for the intersectional nature of disadvantage, which is future work for them.

All of these models have been used to gain a greater understanding of why some people in our organizations are held back, not because of their skills, knowledge, and experience, but because of their demographic characteristics and the systemic bias that goes with it. Systems Dynamics has been used in these cases to explain, spark discussions, and generate solutions. With these tools to hand, perhaps we can all succeed in this world, rather than just a select few.

• Gender segregation dynamics: Women participation and performance in competitive chess in the Netherlands. Presenter: Jeroen Struben.
• Recognizing systemic gender bias: Career advancement case study in a science team. Presenter: Suzanne Manning.
• Gender and ethnic pay inequality in academia: A formal systems dynamics mode. Poster: Inge Bleijenbergh.
• System dynamics modeling to set effective gender targets. Poster: Amin Dehdarian.
• Tipping the scales: Using microworlds to uncover systemic issues driving organizations’ gender pay gap. Presenter: Hugo Herrera.
• A System Dynamics Model to assist leaders to increase diversity in their organizations applied to Twitter’s 25/25 vision. Presenters: Ivan Taylor, Takuma Ono, Saroj Koul

Is System Dynamics so valuable that we should encourage its inclusion in our educational system? This year, presentations at International System Dynamics Conference (ISDC) supported this hypothesis. The President of System Dynamics Society, Shayne Gary, noted a growing trend in appreciating systems thinking as a useful tool to explain complexities. The ever-expanding requirement to cope with a complex world opens room for increased utilization of System Dynamics in our daily life. The power of the method was proved in the global study “Limits to Growth” fifty years ago. Jorgen Randers reflected on this Anniversary by comparing the initial study results with today’s worldwide situation[1]. The project signals one of the most important features of System Dynamics, the capacity to describe phenomena and present their behavior in time, on a global scale.

“Fish Banks has a long history and has been successfully implemented in learning at pre-college, college, and adult levels.”

A major practical application of System Dynamics is as Interactive Learning Environment (ILE). Without the necessity to build a model, these applications allow direct visualization of the system, game playing, storytelling, or simulation of behavior. Notable are two general formats: desktop and online. Will Fisher used the System Dynamics game Fish Banks to explain environmental economics[2]. The students play actors in the fishery system, trying to maintain it. By changing the system parameters they were able to see how the system responds to the altered policies. Results show an easy understanding of the topic, increased awareness about the system, and ‘enthusiasm’ to play. Fish Banks has a long history and has been successfully implemented in learning at pre-college, college, and adult levels.

In another presentation, Juliette Rooney-Varga and her team studied how the use of the online simulation platform helps to change public opinion about climate change, especially at the level of public decision-makers [3]. In their work-in-progress study, they investigated, at which level readymade online interactive medium EN-Roads helps the transformation of insights and action of the politicians towards climate change. Although at the preliminary stage, the results brought some facts that simulation improves overall attitudes toward climate change.

“Lectures that utilize System Dynamics influence change in students’ thinking, enhance capacity to understand calculus, and increase skill in mathematical modeling.” Diana Fischer

Teaching by applying System Dynamics modeling is another practice. Diana Fisher presented work from her long experience in educating pre-college students[4]. She stressed how lectures that utilize the method influence change in students’ thinking, enhance capacity to understand calculus and increase skill in mathematical modeling. Fisher noted that modeling with System Dynamics is not learned quickly but requires support from the institutions and commitment by the learner.

Another approach to practicing System Dynamics in teaching was reported by Zimmermann[5]. She utilizes the participatory group model building method in her classroom environment and has developed instructions to teach System Dynamics through collaborative methods. The benefits of this approach are both learning the use of System Dynamics and also learning group dynamics and participatory processes.

“System Dynamics enhance understanding of complex macro-economic situations, increases soft skills, and improves analytical thinking with a possible wide range of applications with an overall positive impact at the social level.”

Programs to use System Dynamics have been developed at the country level. In Turkey, an environmental and climate change education program at the middle school level has been developed[6]. Students are taught via the direct application and changes in the System Dynamics model. The results are increased knowledge about the subject as well as a proactive attitude to create actions to fight climate change. The students reported interest in seeking environmental-friendly solutions and wanted to continue with the class during the next term. One activity within this program was an online platform for teachers to learn systems thinking and Systems Dynamics. In another case, David Wheat and the Ukrainian team highlighted experiences from the ten-year-long project to learn economics through System Dynamics[7]. The project developed capacities in Ukraine in cooperation with Bergen University. Activities were done in university settings, at the pre-college level, and at the National Bank of Ukraine. They also organized an annual conference, established a competence center, developed a system for scientific cooperation, and incorporated the program into the Ukrainian educational system. Now, without external aid, project members remain enthusiastic and continue the project. The outcomes proved that the use and teaching of System Dynamics enhance understanding of complex macro-economic situations, increases soft skills, and improves analytical thinking with a possible wide range of applications with an overall positive impact at the social level.

“Postponing the decision to involve System Dynamics in the regular curriculum is a loss of opportunity to improve the education of our children and the population in general.”

The 2022 ISDC showed System Dynamics as a useful tool to improve our teaching process with remarkable potential. This didactic instrument supports the learner to focus systemically on the topic and discover internal relationships that sustain or change behavior, expanding cognitive potential through visualizing the nonlinear problems in an array of feedbacks. Teaching System Dynamics extensively from childhood up through the academic levels could enhance children’s holistic understanding of real-world problems, increase their structural thinking capabilities and develop mathematical modeling skills. Our strategy should be to incorporate System Dynamics as a regular tool in our educational system, utilizing it in different formats and adapting the method to each topic. Holistic penetration of System Dynamics in our society was predicted by its founder Jay W. Forester and the method itself was created with the purpose to describe and explain the behavior of any system. Such a powerful method should be considered among the essential capacities for the new era of human development. Postponing the decision to involve System Dynamics in the regular curriculum is a loss of opportunity to improve the education of our children and the population in general.

Presentations: 

[1] Jorgen Randers: “From Limits to Growth to Earth for All – Overshoot and collapse in a 100-year perspective”

[2] W. Fisher: “Teaching the tragedy of open access: a classroom exercise on governing the commons”

[3] J. Rooney-Varga at all: “Can interactive simulation impact what policymakers say and do on climate?”

[4] D. Fisher: “A Model-Building Lesson on Global Warming & Potable Water Availability for a High School Science Class” and “Creating and Building System Dynamics Models From the News (Workshop)”

[5] N. Zimmermann: “Participatory modeling in an introductory systems thinking and System Dynamics class”

[6] M.C. Alibeyoglu et all: “An Educational Program Design: Environmental Education with Systems Thinking and the World Climate Game Project”

[7] David Weat et all: “Learning Economics with Dynamic Modeling in Ukraine, in Collaboration with Norway”

Changed!