Ventana software support forum

Hi, I am trying to create a payoff that MINIMIZES the metric I created that is a function of the gap between my target and actual value, since goal-seeking is not available in Vensim. However, I do not see an option to MINIMIZE payoff, it seems like Vensim automatically maximizes payoff, does not gi...

Yes, the many outflows may be complicating the conveyor effects. I have already tried the simple "rate of progression = patients in treatment / average days in treatment" approach. That is how I had it at first. However, people moved too fast through the system. In reality, there is a mini...

I chose Conveyor following the example in Vensim I found. I need patients to stay a minimum amount of days (ideal treatment duration 1, 2, 3) in each stock, before moving to the next (before the rate of progression can be applied). Is it not Conveyor how you get that effect? That is what the example...

Thank you for your help with the negative values in the stocks. Could you now tell me how to get the same behavior in the stocks for periods 1, 2, and 3 after I stop sending patients into the system please? The graph (second View) shows that period 1 decreases as expected at first, but then continue...

THe second View has the graphs that show the problem very clearly. The top row, graph on the right, that is where the stocks are. Period 1 should be decreasing quickly all the way, and none should go below zero.

Please help. thank you.

I added the IF THEN ELSE because the stocks were getting negative values (past zero). This is how I could fix that. But the conveyor issue was there before. I have uploaded here another version without the IF THEN ELSE in the stocks. Please look at it and answer my question again. And also help me f...

Here is the data file, if that helps:

Hi, I have people progressing through 3 stages of tuberculosis treatment and then completing treatment in this model. Aim 3 w conveyor delay fixed test_testWithNoLTFUAndEntryInLaterStage.mdl I have made it so that after 3624 days, no new patients enter the system. However, when I do this, the stocks...

Hi, I just tried using TIME ****("variable name", -1), but i get this error message: "can only use data and constants in data equations "variable name". Like i said before, I want to use the value calculated at time-1 for "variable name" in the equation, so that ea...

Thank you for your reply. In both those solutions you mention, i would have to call out a specific time point, but I am interested in telling Vensim to use the data value in the previous time point (day-1) at every step (every day), except for time=1, where there would be an initial value that must ...

Hi, I am trying to figure out how to include the data value at time=x-1 into an equation. How do I do that? For variable Z, I want Vensim at time=0 to use =z(initial)+Y*0.01, but at time=2, i'd like it to use =z(at time=1)+Y*0.01. At time=3, i want the equation to read =z(at time=2)+Y*0.01, etc. Wha...

Great, thanks!

Does it make a difference if I use it as "Time" vs. "time"? Capitalization matters?

Hi, I am trying to set up an equation to look like this: y = x+(X*(1-R)*(time-1)), where x is measured in "ideal total days in treatment", R is the rate measured as "days medication was taken/days medication was prescribed", and time is just the measure of time, same as specified...