All,
I'm teaching myself Vensim and working through my first model. I've read a few chapters and studied many of the examples. You don't really learn new tools until you push off on your own. I've hit a couple of stumbling blocks with the tool mechanics and I hope some experts on the forum could add insight and throw your spin onto this simple model.
I thought I would start with something pretty elementary a Lemonade Stand Model (inspired by my entrepreneurial neighbor kids).
Model Scenario:
1. I set this model up to calculate daily and run for 2 years.
2. The kids have up front startup costs: Building Materials, supplies, etc.
3. Revenue comes from the sale of drinks. Drinks start off slow and grow over time (word of mouth, repeat customers, etc.)
4. I want to model the business growth of this scenario.
Issues:
My problems are mostly the vensim tool mechanics.
1. How do I make the DRInks sold to show functional growth? I would like drinks sold to S-curve input function from 10 to 120.
2. How do I setup Units on the flow rates? - Drinks are sold on a daily basis, but the kids have monthly expenses. Vensim seems to be ignoring this units. Shouldn't the tool convert my flow rates automatically?
Also, for the modeling experts: Have I correctly modeled this scenario? The attached file shows the business 'loosing the farm' but this shouldn't be the case.
What variations could I add to teach me more about modeling and make this an educational scenario?
Thanks for advice...
T
Beginner - First Model
Beginner - First Model
- Attachments
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- lemonade_stand_model.mdl
- (2.9 KiB) Downloaded 242 times
Lemonade
I suggest that you look at the system dynamics roadmaps site at http://sysdyn.clexchange.org/road-maps/rm-toc.html especially part 8 (I think) which has a lemonade model ..... there are many similar models about which can provide guidance.
If you are interested in education scenarios look at information here: http://lexchange.org/
Also, are you teaching yourself Vensim, System Dynamics Modeling, or both. Learning the software is only a small part of the task as I think you realize
If you are interested in education scenarios look at information here: http://lexchange.org/
Also, are you teaching yourself Vensim, System Dynamics Modeling, or both. Learning the software is only a small part of the task as I think you realize
limonade
Hi
Joined a modified model.
Not a profitable business!
Regards.
JJ
Joined a modified model.
Not a profitable business!
Regards.
JJ
- Attachments
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- lemonade_stand_model_2.mdl
- (3.45 KiB) Downloaded 241 times