In the 1960s, MIT's Jay Forrester created a simulation that changed how we think about supply chains: the Beer Game.
It revealed that even stable demand can cause wild production swings—now known as the bullwhip effect.
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The game has 4 roles: Retailer, Wholesaler, Distributor & Factory.
Each tries to meet demand & manage inventory—but only sees demand after it’s placed. That delay leads each player to guess, and missteps quickly multiply.
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If the retailer slightly overorders, the wholesaler overreacts, the distributor does the same, and the factory ramps up too much. That overcorrection leads to big swings—causing stockouts or bloated inventories.
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I've been trying to develop a coherent set of equations for the price level in my #systemdynamics model.
My conclusion on the matter: Its important to understand that these theories are not mutually exclusive. 🧵Thread 1/8
Quantity Theory of Money (QTM):
QTM suggests that the price level is directly linked to the money supply. More money = higher prices (assuming other factors remain constant). It's a fundamental idea in monetary economics.🧵Thread 2/8
Monetarism:
Monetarists, like Milton Friedman, stress the importance of controlling the money supply growth rate to maintain stable prices. They argue that excessive money growth leads to inflation.🧵Thread 3/8
I'm about 80% done my National Economic #systemdynamics model, Still have some subsystems that need to be added.
Should have a beta version for download (Using Minsky software) sometime in the next week on my Patreon page. 🧵Thread 1/16
It's stock flow consistent with a foreign sector. There is over 300 variables and parameters at this point. and about 90 feedback loops. I have 17 units of measure including time. 🧵2/16
I found it important to include both domestic and foreign bond holders, as this very much impacts currency values. 🧵3/16
Can we spend our way to a greener future? The World models demonstrate we can't. GDP and CO2 (and other pollutants) fit pretty tightly. We might just spend our way into a climate disaster. Let's be clear were sacrificing our existence for a material standard of living.🧵1/4
In the world model, if I increase capital investment in the aggregate by 25% in 2025, I am able to maintain the material standard of living at the cost of the biosphere. Notice the food ratio does not increase with the additional capital investments. 🧵2/4
Now if I reduce capital investment in aggregate in 2025 by 25%, sure we lose our all-important coping mechanism in the material standard of living, but notice our food ratio holds steady. 🧵3/4
A little message for "some of you economists out there". Let’s say you borrow $100,000 to build a home and the homebuilder banks at your bank. The bank ends up with a $100,000 asset and a $100,000 liability (the loan and the deposit – loans create deposits). 🧵 Thread 1/14
The homebuilder will end up with $100,000 in retained earnings and you will end up with $100,000 in debt. If you net out the investment then the private sector has no change in financial assets and you might presume the private sector is no better off than it was before. 🧵 2/14
Remember, your $100,000 investment resulted in $100,000 in saving for the home builder. But are we actually no better off than we were before? Of course not. You have a new home. 🧵Thread 3/14