Ventana software support forum

In response to Jay Forrests: Once again we seem to arrive at the chasm that seems to separate those who model for insight and those who model for output. There seems to be little common ground between these two perspectives. Jay, as you know I am firmly in the insight camp, however I think you are b...

> Lots of us believe feedback is as > basic as integration to system dynamics. My take was that Kim was saying feedback IS as basic as integration, AND integration (I prefer accumulation) is as basic as feedback. Stock flow maps give us both. CLDs convey part only part of the story. > I am slowly mo...

With the ithink software, HPS ships a model that looks at expansion options
for an hospital emergency care facility and looks at impact on loading in
critical care. Additionally, that model is written up as one of about 15
cases in the Business Applications guide.

Phil Odence
podence@hps-inc.com

Rod Brown is right, time is "a tricky issue." And, in my experience, definitely causes confusion for novice modelers. Maybe this will help clarify. I am pretty confident that it never makes sense to think about time as a stock. It is the ultimate flow; it never accumulates. (Although as Ro...

>Did someone work mixing discrete-event simulation (eg: ARENA software) with >System Dynamics? or do someone know some work about it? If the answer is >yes, was it on the Production/Operations Management field? The ithink and STELLA software have some limited discrete funtionality. It tends to be us...

A step back from Oddurs question... Although mathematically an arrayed formulation works for the hospital system Oddur describes, one shouldnt lose sight of the value of a map that enables interested parties to visualize patient flows between the compartments. In work with hospitals (though, in gene...

[the model is located at http://www.vensim.com/sdmail/models/SD2339.ITM ] The attached ithink model (can be opened with STELLA; you can get a free runtime at www.hps-inc.com, if you dont have the software) handles Oddurs compartment question rather compactly (4 elements). The trick is to calculate h...

> > for example, has babies emerging > >from a "cloud", a device I find extremely counterintuitive, when its > >obviously a circular flow. > Babies are a bad example for explaining a cloud. If you push beyond the JimHs physical/chemical explanation you get into all kinds of metaphysical mu...

John, I believe there are some pretty simple explanations. Ill try to articulate them below. If it would help, I could throw together a simple ithink model which would do a better job than the words. Phil Odence HPS A typical s-shaped growth model is structured as a customer stock built by a gaining...

RE: Carmen Husts inquiry about hospital models Carmen, You might check out a model HPS developed that looks at patient flow from Emergency Care to Critcal Care and out. A version is available with the ithink demo availble on the HPS website (www.hps-inc.com). Its also written up in detail in the Bus...

Gary H beat me to it. Had I been quicker, I would have written something
very close to Garys words on the role of LEs in making SD insights
accessible. Thanks, Gary.

Phil Odence
High Performance Systems
podence@hps-inc.com

A few thoughts regarding Sauds inquiry about making model struture transparent: - Lead with behavior, then with structure. Weve found that people get a lot more interested in structure, once they experienced some behavior that they wish to have explained. - Use simplified versions of structure. Gene...

I think the feedback issue is often related to a timeframe component as well. Queuing models may run over a hours or days, but if it takes weeks or months for potential queue-ees to build up expectations for queuing times, that model would not/could not take that into account except as an exogenous ...

Reply to: But what do I do if I dont have a master handy? Fr: Phil Odence, podence@hps-inc.com In response to John Ss and Jim Ts discussion about finding someone else to work with: Study at the foot of the master is great, but even though there are twice as many feet as masters, they are still scarc...

Reply to: RE>>Example of Simulation Success (SD0194) From: Phil Odence, podence@hps-inc.com Regarding Jim Hines and Bill Cutlers discussion of Americas Cup sloop design. *********** yes and... I underscore Jims reaction to Bills excellent example. The other point raised by the example is that in boa...