Vensim

Vensim provides a graphical modeling interface with stock and flow and causal loop diagrams, on top of a text-based system of equations in a declarative programming language. It includes a patented method for interactive tracing of behavior through causal links in model structure (the patent expired in 2012),{{cite web|url=http://vensim.com/causal-tracing/|title=Vensim Causal Tracing™|website=Vensim - Ventana Systems}}{{cite web|url=https://patents.google.com/patent/EP0527907A1/en?oq=causal+tracing|title=Simulation system employing causal tracing. US Patent Application EP19910909851, Feb. 26 1991}}{{cite web|url=http://patents.justia.com/patent/5428740|title=Applying successive data group operations to an active data group. Patent # 5,428,740|website=Justitia.com}} as well as a language extension for automating quality control experiments on models called Reality Check.{{cite journal|title=Reality check: A bridge between systems thinking and system dynamics|first1=David W.|last1=Peterson|first2=Robert L.|last2=Eberlein|journal=System Dynamics Review|volume=10|issue=2–3|pages=159–174|year=1994|doi=10.1002/sdr.4260100205|doi-access=free}}

The modeling language supports arrays (subscripts) and permits mapping among dimensions and aggregation. Built-in allocation functions satisfy constraints that are sometimes not met by conventional approaches like logit.[http://vensim.com/allocation-by-priority-alloc-p/ Vensim Allocation by Priority] It supports discrete delays, queues and a variety of stochastic processes.

There are multiple paths for cross sectional and time-series data import and export, including text files, spreadsheets and ODBC. Models may be calibrated against data using optimization, Kalman Filtering{{cite thesis|title=Hypothesis, estimation, and validation of dynamic social models: energy demand modeling|last1=Peterson|first1=David Walter|year=1975|type=Ph.D.|publisher=Massachusetts Institute of Technology. Dept. of Electrical Engineering and Computer Science|hdl = 1721.1/27424}} or Markov chain Monte Carlo methods. Sensitivity analysis options provide a variety of ways to test and sample models, including Monte Carlo simulation with Latin Hypercube sampling.

Vensim model files can be packaged and published in a customizable read-only format that can be executed by a freely available Model Reader. This allows sharing of interactive models with users who do not own the program and/or who the model author does not wish to have access to the model's code base.{{cite web|url=http://vensim.com/vensim-model-reader/|title=Vensim Model Reader|website=Vensim - Ventana Systems}}

Vensim is general-purpose software, used in a wide variety of problem domains. Common or high-profile applications include:

• Transportation and Energy{{cite conference|title=Evaluating NGATS Research Priorities at JPDO|first1=Daniel|last1=Goldner|first2=Sherry|last2=Borener|conference=6th AIAA Aviation Technology, Integration and Operations Conference (ATIO)|year=2006|location=Wichita, Kansas, US|doi = 10.2514/6.2006-7726}}{{cite journal|title=Transition Challenges for Alternative Fuel Vehicle and Transportation Systems|first1=Jeroen|last1=Struben|first2=John D.|last2=Sterman|journal=Environment and Planning B: Planning and Design|year=2008|volume=35|issue=6|pages=1070–1097|doi=10.1068/b33022t|bibcode=2008EnPlB..35.1070S |hdl=1721.1/102784|s2cid=8801851 |hdl-access=free}}
• Business Strategy{{cite journal|title=Getting Big Too Fast: Strategic Dynamics with Increasing Returns and Bounded Rationality|first1=John|last1=Sterman|first2=Rebecca|last2=Henderson|first3=Eric|last3=Beinhocker|first4=Lee|last4=Newman|journal=Management Science|year=2007|volume=53|issue=4|pages=683–696|doi=10.1287/mnsc.1060.0673}}
• Health{{cite journal|title=Selecting a Dynamic Simulation Modeling Method for Health Care Delivery Research—Part 2: Report of the ISPOR Dynamic Simulation Modeling Emerging Good Practices Task Force|author=Deborah A. Marshall|display-authors=etal|journal=Value in Health|year=2015|volume=18|issue=2|pages=147–160|doi=10.1016/j.jval.2015.01.006|pmid = 25773550|doi-access=free}}
• Security and Terrorism{{cite journal|title=Radicalization under deep uncertainty: a multi-model exploration of activism, extremism, and terrorism|last1=Pruyt|first1=E.|last2=Kwakkel|first2=J. H.|year=2014|journal=System Dynamics Review|volume=30|issue=1–2|pages=1–28|doi=10.1002/sdr.1510}}
• Project Management{{cite journal|title=Modeling the rework cycle: capturing multiple defects per task|last1=Rahmandad|first1=H.|last2=Hu|first2=K.|journal=System Dynamics Review|volume=26|issue = 4|pages=291–315|year=2010|doi=10.1002/sdr.435}}
• Marketing Science in Pharmaceuticals and Consumer Products{{cite web|url=http://www.ventanasystems.com/model_typeslist/marketing/|title=Ventana Systems, Inc. Marketing Models|website=Ventana Systems}}
• Logistics{{cite journal|url=https://www.researchgate.net/publication/227616857|title=Upstream Volatility in the Supply Chain: The Machine Tool Industry as a Case Study|first1=Edward G. Jr.|last1=Anderson|first2=Charles H.|last2=Fine|first3=Geoffrey G.|last3=Parker|journal=Production and Operations Management|volume=9|issue=3|pages=239–261|year=2000|doi=10.1111/j.1937-5956.2000.tb00136.x|hdl=1721.1/1644|citeseerx=10.1.1.38.7001}}
• Environment{{cite web|url=https://www.climateinteractive.org/tools/c-roads/|title=The C-ROADS model|website=Climate Interactive|date=2014-01-02}}{{cite journal|doi=10.1016/j.envsoft.2012.06.004|title=Management flight simulators to support climate negotiations|first1=John D.|last1=Sterman|first2=Thomas|last2=Fiddaman|first3=Travis|last3=Franck|first4=Andrew|last4=Jones|first5=Stephanie|last5=McCauley|first6=Philip|last6=Rice|first7=Elizabeth|last7=Sawin|first8=Lori|last8=Siegel|journal=Environmental Modelling & Software|volume=44|year=2013|pages=122–135|bibcode=2013EnvMS..44..122S }}{{cite journal|title=System dynamics modelling of the Endangered African penguin populations on Dyer and Robben islands, South Africa|first1=Florian|last1=Weller|first2=Richard B.|last2=Sherley|first3=Lauren J.|last3=Waller|first4=Katrin|last4=Ludynia|first5=Deon|last5=Geldenhuys|first6=Lynne J.|last6=Shannon|first7=Astrid|last7=Jarre|journal=Ecological Modelling|volume=327|year=2016|pages=44–56|doi=10.1016/j.ecolmodel.2016.01.011|bibcode=2016EcMod.327...44W }}

• Comparison of system dynamics software
• Computer simulation
• List of computer simulation software
• Monte Carlo simulation

{{Reflist|30em}}

• [http://vensim.com Official Vensim web site]
• [http://ventanasystems.com Official Ventana Systems, Inc. web site]
• [http://simulation.tbm.tudelft.nl/ema-workbench/contents.html Exploratory Modelling and Analysis (EMA) Workbench]
• [http://tools.systemdynamics.org/sdm-doc/ SDM-doc documentation tool]{{cite journal|last=Martinez-Moyano|first=I. J.|year=2012|title=Documentation for model transparency|journal=System Dynamics Review|volume=28|issue = 2|pages=199–208|doi=10.1002/sdr.1471|doi-access=free}}
• [http://forio.com Forio.com - host for online Vensim models]

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