methodatlas

Systems Thinking Analysis method

System Dynamics Simulation

Translates a dynamic hypothesis into stock-flow equations and tests scenarios.

A system dynamics simulation defines stocks, flows, auxiliaries, units, and initial values. Calibration, dimensional checks, and sensitivity analysis limit false precision.

Core question
What feedback and accumulation structure generates the behaviour, and how do scenarios respond?
Participants
1-5 Modellierende, Stakeholder asynchron
Time
Mehrere Tage bis Wochen

System Dynamics Simulation uses stock-flow model with dimensionally consistent equations, calibration, and sensitivity. Assessments remain justified and context-bound.

Paper illustration of System Dynamics Simulation with its method-specific working model.
  1. Reference mode

    Reference mode

    Define problem behaviour and horizon as data curves.

  2. Build stock-flow

    Build stock-flow

    Model stocks, flows, feedback, and delays with equations.

  3. Validate model

    Validate model

    Test structure, extreme conditions, and historical fit.

  4. Run scenarios

    Run scenarios

    Compare interventions and parameter sensitivity over time.

Maintain model version, parameter sources, and deviations between simulation and observation.

A good fit when

For accumulative problems with feedback and delay where decisions depend on behaviour over time.

Ideal for

  • Public policy
  • Climate and energy models
  • Business model stress testing

Not good for

  • Fast operational decisions

Outputs

  • validated stock-flow model

    validated stock-flow model with traceable sources, assumptions, and domain decisions.

  • Decision and review trail

    Owners, dates, and next review for validated stock-flow model.

validated stock-flow model

Fictional worked example

stock-flow model with dimensionally consistent equations, calibration, and sensitivity as a precise working structure with a fictional example.

Reference mode

Variable · unit · time series

Open tickets, daily, 26 weeks.

Stock and flows

Stock · inflow · outflow

Backlog; new/resolved tickets per day.

Equations

Formula · unit · source

Δt=1 day; Out=min(Stock/Δt, Agents×Productivity) [tickets/day]; State next=State+(In−Out)×Δt.

Validation and scenario

Tests · range · intervention

±20% sensitivity; reduce recurrence from W6.

The example demonstrates the domain logic of System Dynamics Simulation; worksheets remain blank.

MIT System Dynamics in Education Project: Road Maps

First step

Start with the core question: What feedback and accumulation structure generates the behaviour, and how do scenarios respond?

Open the method guide

Deep dive

Purpose

System Dynamics Simulation makes assumptions about time, delay, and feedback testable through experiments. It draws relationships, patterns, and feedback loops. The result is captured as a simulation model and scenario reports.

How it works

First, stocks, flows, rules, and delays are formulated as a simulation model. The team then tests various scenarios and varies the assumptions until visible patterns emerge. The results help make robust decisions against seemingly simple but deceptive linearizations.

In detail

System Dynamics Simulation goes back to Jay Forrester and combines qualitative models such as Causal Loop Diagrams with quantitative stocks, flows, and auxiliary variables. Tools such as Vensim, Stella, or Simantics calculate scenarios over time and enable policy tests. It is often used in sustainability, public policy, and strategy consulting.

Facilitation

Start with the stock-and-flow diagram. Use sensitivity analysis instead of emphasizing single-point forecasts. Keep assumptions explicit.

The method guide walks execution through 4 phases, timing, 4 pitfalls, and clear stop criteria.

Open method guide

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Sources and topics

Topics
Artifact templates
System Dynamics Simulation: WorksheetPlan System Dynamics Simulation around its domain steps and the concrete decision question.
markdown

system-dynamics-simulation-working-template.md

Plan System Dynamics Simulation around its domain steps and the concrete decision question.

System Dynamics Simulation: Worksheet

Question

To be confirmed

Desired outcome

To be confirmed

Scope

Full initiative Time: Multiple sessions over 2–6 weeks

Complete this worksheet on paper or in your own document during the work.

Preparation for this scope

Method setup

  • Materials: Reference mode and time series, causal hypothesis, parameter sources and units, shared workspace, source links, and decision log.
  • Roles: Modeler · domain experts · data analyst · decision owner
  • Advance information: Collect Reference mode and time series, causal hypothesis, parameter sources and units in advance and mark open assumptions.
  • Overall time needed: Multiple sessions over 2–6 weeks
  • Setup: Prepare stock-flow model with dimensionally consistent equations, calibration, and sensitivity visibly and calibrate assessment terms before starting.

Prepare for the work steps

Reference mode: Reference mode

  • Reference mode and time series
  • causal hypothesis
  • parameter sources and units

Build stock-flow: Build stock-flow

  • reference mode
  • causal hypothesis
  • parameter sources and units

Validate model: Validate model

  • simulation model
  • causal hypothesis
  • parameter sources and units

Run scenarios: Run scenarios

  • validation record
  • causal hypothesis
  • parameter sources and units

validated stock-flow model

Reference mode

Variable · unit · time series

...

Stock and flows

Stock · inflow · outflow

...

Equations

Formula · unit · source

...

Validation and scenario

Tests · range · intervention

...

Enter only real input, sources, and decisions.

MIT System Dynamics in Education Project: Road Maps

Reference mode: Reference mode

Expected artifact: reference mode

reference mode · source · uncertainty · next decision

Entry:

...

  • Are measure, unit, and horizon clear?

Build stock-flow: Build stock-flow

Expected artifact: simulation model

simulation model · source · uncertainty · next decision

Entry:

...

  • Does every equation pass dimensional analysis?

Validate model: Validate model

Expected artifact: validation record

validation record · source · uncertainty · next decision

Entry:

...

  • Was the model tested against uncalibrated data?

Run scenarios: Run scenarios

Expected artifact: scenario comparison

scenario comparison · source · uncertainty · next decision

Entry:

...

  • Do assumptions and ranges remain visible?

Open questions and next steps

...

Method guide: https://methodatlas.meierhoff-systems.de/en/methods/system-dynamics-simulation/run-sheet

Alternatives and neighbors

Fitting alternatives with decision guidance, followed by other related methods.

All methods
Constraints and origin
HighAsyncMehrere Tage bis Wochen

Profile

Method form
Analysis method
Participants
1-5 Modellierende, Stakeholder asynchron
Time
Mehrere Tage bis Wochen
Maturity
Canonical
Origin
Jay W. Forrester
Scenario Planning method illustration showing its working structure
Next up: Scenario Planning