#modelthinking

[secrettoadspire]

Dr. Richard C. Larson’s Legacy in Engineering, Research, and Model-Based Decision-Making.

Dr. Richard C. Larson’s Dr. Richard C. Larson’s professional life is a beacon of what can be accomplished when intellectual passion is joined with a lifelong commitment to using knowledge to address real-world challenges. Known globally for his seminal contributions to Operations Research and Industrial Engineering, Dr. Larson has crafted a career that harmoniously integrates scholarship, leadership, and practical influence. A Pinnacle Professional Member of the Inner Circle of Excellence, he has spent decades influencing engineering education, research, and practice.

Academic Roots and Intellectual Journey

Dr. Larson’s association with the Massachusetts Institute of Technology (MIT) is profound and long-standing. Having received his B.S. in 1965, M.S. in 1967, and Ph.D. in 1969, he committed his professional life to pushing research forward and grooming future leaders. His work has consistently been about connecting theory to practice — translating mathematical models into practical solutions for public safety, city planning, and even decision-making in everyday life.

His instruction is not merely about frameworks and equations; it’s about developing a mindset. To Dr. Larson, model thinking is a world understanding — an approach that assists in simplifying complexity and developing strategies that succeed in real life.

Leadership and Professional Impact

Throughout his career, Dr. Larson has held powerful leadership positions such as president of the Operations Research Society of America (ORSA) and the Institute for Operations Research and the Management Sciences (INFORMS). His leadership in modernizing the discipline and motivating a generation of researchers, policymakers, and industry practitioners influenced many.

Outside of academia, he co-founded Public Systems Evaluation, Inc. and Structured Decision Corporation, whose models informed urban policy and made systems better in cities such as New York and St. Louis. This mix of consulting and teaching was his way of accepting that intellectual tools must directly serve society — rather than wait for research papers.

A Mission to Bring Models to the Public

In 2023, Dr. Larson wrote Model Thinking for Everyday Life: How to Make Smarter Decisions, a new book aimed at enabling readers to use analytical thinking in everyday decisions. From getting out of the house for an appointment on time to balancing your budget to making tough trade-offs, the book demonstrates how models can make life more knowable and manageable.

This book is not merely intellectual — it’s a cultural invitation. Dr. Larson wants to make model thinking accessible as a skill, not only for scientists or engineers. By making this knowledge available widely through prominent booksellers, he wants to democratize decision-making tools for individuals of any age.

Personal Life and Values

Although professionally successful, Dr. Larson is humble. He attributes a lot of his success to his late wife, M. Elizabeth Murray, whose support and collaboration stood by him through it all. He also gives credit to his children — Erik, Evan, and Ingrid — for continuously believing in his work and for encouraging him to continue learning, teaching, and venturing.

Legacy and the Road Ahead

Numerous former students of Dr. Larson are now leaders in government, academia, and industry, and carry on his mission of using model thinking to address the challenges of society. He has not only influenced careers but also the ethics and analytical strategies of countless professionals through mentorship.

Even now, Dr. Larson isn’t slowing down. He keeps writing, teaching, and spreading the word for a world in which better choices are made by careful design and strong analysis. His own career is testament to how intellectual discipline, when combined with a sense of mission, can bring lasting change to society.

[platospride-blog]

Dynamic Models of Segregation - Thomas C. Shelling

Thomas Schelling in the late 1960s and early 1970s set out to investigate segregation effects with a specific interest in racial segregation produced by individual behaviour (independent of potentially further organized behaviour or economical effects like separating rich from poor, educated from uneducated etc. or even other additional effects and behaviours). Ultimately, his analysis extended to a general level where his effects and theory could be reproduced and would be applicable in any environment where the distinction of the examined variable (like in this case race) is two-fold (black or white), exhaustive (everybody is either black or white), and recognizable (it is externally obvious if somebody is black or white). In his own words: "This paper, then, is about those mechanisms that translate unorganized individual behavior into collective results." (page 3).

Roughly, the paper is divided into two parts. In the first part Shelling simply considers the individual as happy or unhappy with his current neighbourhoods distribution. If at least 50% of somebody's neighbours are the same color of him he is happy and stays. If less than 50% are of the same race he moves somewhere else (Note that every position can either be white, black or currently empty). Shelling then analyzed how this played out over a certain time period with people moving or staying based on this logic.

Several further variations were analyzed including "Intensity of Demand for Like Neighbors" (preference not simply min. 50% but other distributions like minimum 33% etc.), "Unequal Demands" (Blacks and Whites have different preferences like Whites min. 50% and Blacks min. 33%), "Unequal Numbers, Equal Demands" (symmetrical preferences but not the same number of Blacks and Whites in the population), "Size of Neighborhood" (how far-reaching the neighborhood is defined, immediate neighbors only or further additional neighbors as well), "Congregationist Preferences" and "Integrationist Preferences" (minimum number of other race people required to be happy). Furthermore, effects regarding the "Population Densities" of states were analyzed (how many spaces remained unoccupied after both groups reached satisfactory distributions).

Key results were that there were much stronger segregation effects of "ratios of like neighbors to opposite neighbors [...] upwards of four to one for demands of one-half or more [instead of two to one which 50% would naively suggest], and less than 1.5 for demands of about one-third [i.e. typically minimum 4.5 instead of about 3 out of 9 being the same color for that constraint]." (page 16/17)

Furthermore, it became obvious that there is a strong tendency that "everybody [...] moves toward whatever cluster of like-colored individuals he can find; and the number of such clusters declines disproportionately as the minority becomes smaller. The result is that the minority forms larger clusters, large enough to cause even a tolerant majority to become locally dissatisfied." (page 19) As these clusters are the only clusters which satisfy the minorities search for similar individuals this additionally increases the density in such spots (i.e. not only the Black/White ratio changes but also the number of unoccupied spots drastically declines) and further amplifies the segregation effect beyond the otherwise from a macro perspective required level. Concerted action could avoid this but as under this model everybody solely acts from his individual perspective it is not possible to create smaller alternate clusters satisfying everybody's individual requirements.

In the second part of his paper Shelling analyzed just one bigger neighborhood with people either being in the neighborhood or outside of it. In this section he analyses population groups and their preferences across a continuuom of completely tolerant to completely intolerant attitudes. In this section of the paper he moves from looking at individual actors and determining their action independently for every one of them according to the rules of the model towards solely focusing on ratios. Again, he shows that there usually is an equilibrium in the extremes (pure White or pure Black populations). Based on the distribution of tolerance and size as well as after introducing some other measures like an externally enforced constraint of a maximum number of residents of a certain type there can also be other equilibrium states which are mixed. He notes though, that in general, "for a stable mixture, the minority must be the more tolerant of the two groups." (page 37)

Finally, Shelling finishes this section with some observations regarding tipping points. His model shows that while tipping can occur as a cumulative effect of natural turn-over, limited supply (if the initial neighborhood didn't have any unoccupied spaces) or other cases (e.g. in some cases there might be a big pool of potentially interested people from the other group to move into this neighborhood while in other cases moving in from the other group would be purely accidental or coincidental), this effect is independent of the actual tolerance value. "In none of the cases shown does any important discontinuity necessarily occur at the modal or typical tolerance value." (page 40)

Read the full paper here: http://www.stat.berkeley.edu/~aldous/157/Papers/Schelling_Seg_Models.pdf

[claudia-mooc-ing]

Start of Coursera Model Thinking course with Scott E Page, U of Michigan. This screen shot from the Where are you from? thread in the General discussion forum sums up in a single image something quite unique about the mooc-ing of education. It's really quite an extraordinary thing to witness as a participant. (I'm not getting into the nuances of MOOCs here....I'll leave that to @audreywatters.)