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.
SpaceX was riding high when I posted my dataviz of tech giant market capitalization vs. revenue. By this morning, it was down from its peak by about 50%. Click to enlarge interact. Note that this is not updated in realtime. Is this the bottom? In a rational universe, I think not, because even its Continue reading "How far could SPCX fall?"
TLDR; you can use a mature model with lots of detail and vetted data to produce garbage output by feeding it a dumb scenario and willfully misinterpreting the answers.
Sena Evren has a nice article on the state of AI intellectual property ownership. There s more detail on the caselaw in this congressional memo. Since SD models are essentially code, I think it s largely applicable to models built with AI assistance. Per the article, there are a lot of unsettled areas. Regarding #3, that AI Continue reading "Who owns your model?"
I think this chart shows pretty well just how wild the SpaceX IPO is. Extrapolate at the slopes of other mega tech companies: if it had Amazon s revenue today, it would be almost as large as the entire S P500 by market cap. At present revenue, its multiple is massive compared to Meta, Nvidia and Amazon. Continue reading "Lost in SpaceX"
My kid (an actual rocket scientist) told me the AI he had access too was pretty bad at linear algebra. I ve had eigenvalues on my mind lately, so I thought that would be a good opportunity for a test. I asked Copilot about a conjecture, that a subset of stocks in a system having nontrivial Continue reading "Arguing Linear Algebra with Copilot"
Sometimes the best model is the data, but all data are wrong! A big part of validation is detecting and correcting errors in data. I ve recently run across an interesting example. I m working on Chronic Wasting Disease in deer, which essentially combines an epidemiology model with a deer population model, surrounded by some social and Continue reading "Modeling to detect data problems"
I often run across interesting time series that make good reference mode diagrams. Reference modes, in System Dynamics jargon, are plots that neatly summarize the real-world problem behavior that motivated a model (VanderWerf, 1981). There s a lot of variation in practice, but drawing reference modes is often a nice way to get started on model Continue reading "Reference modes"
The Nazi party s share of elections roughly doubled each year from their first parliamentary contest in 1928 to full dictatorship in 1933.
Excerpt of letter to George Washington from Lewis Nicola, 1782: https://founders.archives.gov/documents/Washington/99-01-02-08500 This war must have shewn to all, but to military men in particular the weakness of republicks, the exertions the army has been able to make by being under a proper head, therefore I little doubt, when the benefits of a mixed government Continue reading "George…
In contemplating the causes, which may disturb our Union, To the efficacy and permanency of your Union, a Government for the whole is indispensable. No alliances, however strict, between the parts can be an adequate substitute; they must inevitably experience the infractions and interruptions, which all alliances in all times have experienced. Sensible of Continue reading "George Washington on the…