# Model Fidelity **Domain:** Modeling / Simulation / Digital Twins **Doc Type:** Technical Concept Node **Maturity:** Developed ## Definition **Model fidelity** is the degree and kind of correspondence between a model and the system it represents for a defined purpose. Fidelity is multidimensional. A model may represent geometry accurately while simplifying behavior, capture average dynamics while missing rare failures or predict one outcome well while being invalid for another decision. ## Governing Variable Fidelity governs warranted reliance: which questions a model can answer with acceptable error and uncertainty. ## Relation to Governance More detail is not automatically better. A fit-for-purpose model should preserve the variables and relationships material to its authorized use while making omissions visible. [[wiki/Digital Twin|Digital Twin]] operationality therefore depends on declared purpose, validation and uncertainty rather than a claim of perfect mirroring. ## Failure Modes False precision, unvalidated transfer, stale calibration and use outside scope can turn apparent fidelity into [[wiki/Model Error|model error]]. High fidelity in measured variables can also conceal the absence of unmeasured human or ecological context. ## Related Ontology [[wiki/Model Error|Model Error]] · [[wiki/State Estimation|State Estimation]] · [[wiki/Digital Twin|Digital Twin]] · [[wiki/Counterfactual Simulation|Counterfactual Simulation]]