Ventana software support forum

Hi, I have never met Jay personally but I have soft spot in my heart for inventors like him. I can imagine that at the end of his days he realized what a "monster" called System Dynamics he created. "Monster" that on the surface appears so simple that is being introduced at eleme...

I know Jay Forrester as well, from videos and books. My impression of him is that he was very strict about System Dynamics implementation. For example: "flow" is always function of time: liters/hour, but "rate" could be anything: people/square_meters. Anyhow, I misread the whole ...

The Vensim help files are telling different story. Stock and Flow are not even mentioned in the Glossary of Terms but Levels and Rates are everywhere. Stock and Flow have much broader meaning then Levels and Rates and they are correct. Jay Forrester must be turning in his grave at the thought of wha...

Why did you redefine the hallmark of System Dynamics?
From: Stock and Flow diagrams
To: Level and Rate diagrams

After a long break from Vensim, I am trying to use version 10.1.3. I noticed that positioning of labels on Flows is not working anymore: "Above, Below ..." (see attached snapshot). I checked the previous versions of Vensim and this feature was working in 9.1.1 and 9.2.4 but was broken in 9...

I downloaded latest version of Vensim 9.4.0 but I can't install it because I am getting this error (see attachment).

Maintenance is valid until May, 2024.
My Visa was charged for the maintenance.
What is the problem?

On the attached screenshot I was trying to show that the old graphics was permanent, regardless of the skin that I have selected (old or new). I traced this problem to Vensim messing up Windows Registry. If you want to repeat this bug then switch old-new-old let say 20 times. However, I managed to r...

Is my attached image not clear that I should not see a new graphical GUI and the old style "stock and flow" diagram at the same time? I have version 9.0 installed and it's telling me that I have the latest version installed. I will disregard this message an install 9.1 to a separate folder...

Reply to issue #1. This is what I have : - PLE+ version 9.0.0. - new GUI interface but old symbols (see attachment) This is what I need. Procedure (guidance) on how to install two completely independent versions of Vensim, 9 and 8. My understanding of this process is: - uninstall current version 9.0...

After switching Vensim few times from v9 to v8 and back, Vensim is now stack permanently in old version regardless of the GUI I select. I wish switching would work flawlessly but I prefer old version of Vensim because it has functionalities that were removed in v9. The changes that I would like to s...

I have no interest in building realistic Population Models but if I would have to build one then I would include government as the controlling entity. Governments develop long term demographic forecasts and they use them to control population size through social policies (e.g. from ‘draconian rule o...

Year 2022 marks the 50th anniversary of the introduction of the Population Model, the most popular model in system dynamics. The model was first published in a very popular book at that time, “The Limits to Growth” (1972) by Meadows. Book was a success but nobody noticed that the Population Model wa...