Lecture D-E - Midterm Review (2020-02-25)

This lecture reviews all content in Units A, B, C, and D in SOS 212 as preparation for the midterm. These topics cover modeling fundamentals, causal loop diagrams, system archetypes, and basic stock-and-flow diagrams (as well as numerical integration of dynamical system models in general). Examples are given within the slides as well as separately on top of a sample midterm and midterm review problems distributed to the students before the lecture.

Link to Spring 2019 sample midterm with annotations made while in class:

https://www.dropbox.com/s/yjlzhjxooe9oqsu/SOS212-LectureDE-2020-02-25-Annotated_MidtermB_Examples.pdf?dl=0

Link to Midterm Review problems with annotations made while in class:

https://www.dropbox.com/s/9zasvdppu0f2d2g/SOS212-LectureDE-2020-02-25-Annotated_MidtermReview_Examples.pdf?dl=0

Lecture D4 - Morecroft (2010, Chapter 3), "Modelling Dynamic Systems" (2020-02-20)

This lecture is focused primarily on the content of Chapter 3 from Morecroft (2010) on "Modeling Dynamic Systems." We start with a very brief Insight Maker tutorial and then drill down into the main content of the chapter. We introduce stocks, flows, and coordinating networks of links between them. We also motivate how stock-and-flow diagrams when combined with computer simulation (or numerical integration) provides an alternative methodology for investigating dynamical systems that does not require the formal methods of calculus. We end with a basic dynamical systems model of a city allocating police to manage the illegal drug market and discuss basic verification and validation (V&V) with respect to the graphs that come out of the simulated model.

Lecture D3 - Stock-and-Flow Diagrams in Vensim and Insight Maker (2020-02-18)

In this video, we cover more detailed descriptions of "stocks", "flows", and "converters" as well as how they are shown in stock-and-flow diagrams and how to annotate them using reasoning from causal loop diagrams (CLDs). Connections to the underlying calculus concepts (derivatives and initial-value integration problems) are also made. We then conclude with a brief introduction of how to draw and simulate stock-and-flow diagrams in Vensim and Insight Maker.

Lecture D2 - Introduction to Numerical Simulation of Dynamical Systems, Part 2 (2020-02-13)

In this lecture, we continue our discussion of basic numerical methods (implemented in Excel) to simulate (deterministic) dynamical systems. We start with the bacterial example with only births (reproduction events) and add in deaths. We then discuss the effect of changing the time step ("dt"). We then conclude with an in-class exercise simulating the trajectory of a toilet filling up after a flush.

Lecture D1 - Introduction to Numerical Simulation of Dynamical Systems, Part 1 (2020-02-11)

In this lecture, we introduce basic numerical methods for simulating (or "integrating") dynamical systems models, like those specified by ordinary differential equations (ODE's) or System Dynamics Models formulated graphically as stock-and-flow diagrams. The lecture starts with a compound interest example (a model of how money grows in a "bank" -- with the bank balance playing the role of a stock and the interest generated over a year playing the role of a flow) and demonstrates how more general continuous dynamics (like the average population trajectory of bacterial growth) can be approximated like money growing in a bank via compound interest. All examples are done in a spreadsheet program, like Microsoft Excel, with hints of how the models will later be put into a formal System Dynamics Modeling tool like Vensim or Insight Maker in the form of stock-and-flow diagrams.

Lecture C2 - "Applying Systems Archetypes" from Kim and Lannon (1997) (2020-02-06)

In this lecture, which is based on "Applying Systems Archetypes" from Kim and Lannon (1997), we discuss four different ways that CLD systems archetypes can be used when analyzing systems, recognizing problems, and developing interventions. This lecture sets us up for the development of stock-and-flow models for system dynamics simulation modeling starting in the next lecture.

Lecture C1 - Building More Complex Causal Loop Diagrams (2020-02-04)

This lecture covers the process of building more complex causal loop diagrams. We first start with behavior over time trajectories and use them to guide what loops (and then what variables) should be included in our models. We then flip to a perspective where we focus on what kind of problem we're interested in modeling and add loops until we form basic archetypes (with expected behaviors over time) that we can further customize.