Verification, Validation, and Accreditation (VV&A) are three interrelated but distinct processes that gather and evaluate evidence to determine whether a model or simulation should be used in a given situation and establishing its credibility. The decision to use the simulation will depend on the simulation’s capabilities and correctness, the accuracy of its results, and its usability in the specified application. 
The purpose of VV&A is to assure development of correct and valid simulations and to provide simulation users with sufficient information to determine if the simulation can meet their needs. VV&A processes are performed to establish the credibility of the models and simulations. Credibility depends on simulation and also depends on the accuracy of a simulation. The decision on whether or not a simulation provides the necessary degree of accuracy depends not only upon the inherent characteristics of the simulation, but also upon how the simulation will be used, and upon the significance of any decisions that may be reached on the basis of the simulation’s outputs. 
Credibility for a simulation depends on its correctness, the level of confidence that its data and algorithms are sound, robust, properly implemented, and that the accuracy of the simulation results will not substantially and unexpectedly deviate from the expected degree of accuracy. Credibility also depends, on its usability. Usability are the factors related to the use of the simulation, such as the training and experience of those who operate it, the quality and appropriateness of the data used in its application, and the configuration control procedures applied to it. 
The official DoD definitions for these processes are: 
- Verification: The process of determining that a model implementation and its associated data accurately represent the developer’s conceptual description and specifications.
- Validation: The process of determining the degree to which a model and its associated data provide an accurate representation of the real world from the perspective of the intended uses of the model.
- Accreditation: The official certification that a model, simulation, or federation of models and simulations and its associated data is acceptable for use for a specific purpose.
See the Verification, Validation & Accreditation Recommended Practice Guide for more detailed information.
The DoD VV&A Documentation Tool (DVDT) addresses the need to capture (VV&A) information in a consistent form with consistent content.
Military Standards related to VV&A
Standardized DoD VV&A documentation templates are located in MIL-STD-3022 “Documentation of (VV&A) for Models and Simulations”.
- DI-MSSM-81750 Department of Defense (DoD) Modeling and Simulation (M&S) Accreditation Plan
- DI-MSSM-81751 Department of Defense (DoD) Modeling and Simulation (M&S) Verification and Validation (V&V) Plan
- DI-MSSM-81752 Department of Defense (DoD) Modeling and Simulation (M&S) Verification and Validation (V&V) Report
AcqLinks and References:
- Modeling & Simulation Guidance for the Acquisition Workforce – Oct 208
- DoD Instruction 5000.61 “DoD M&S Verification, Validation, and Accreditation (VV&A)” – 9 Dec 2009
- DoD 5000.59 “DoD Modeling and Simulation (M&S) Management” – 8 Aug 2007
- DoD “M&S Body of Knowledge (BOK)” – June 2008
- DAU “Test and Evaluation Management Guide” – Chapter 14 – Jan 2005
- SMC “Systems Engineering Handbook” – 15 Jan 2004
- DoD 5000.59-M “M&S Glossary” – Jan 1998
- DoD “M&S Glossary” – 1 Oct 2011
- Acquisition Modeling and Simulation Master Plan – 17 April 2006
- White Paper: JHU APL “Best Practices for the Development of M&A” – June 10
- White Paper: Introduction to Modeling and Simulation by Anu Maria
- White Paper: Introduction to Modeling and Simulation
- Presentation: Manager’s Guide to the High Level Architecture (HLA) for M&S – 11 May 2009
- Website: Air Force Agency for Modeling and Simulation
- Website: Army Modeling and Simulation Office
- Website: DoD M&S Coordination Office (MSCO)
- Website: DoD M&S Catalog
- Website: Simulate Interoperability Standards Organization (SISO)