I/ITSEC Tutorial #1019 The Basics of the M&S VV&A Process

I/ITSEC Tutorial #1019 The Basics of the M&S VV&A

ProcessSimone Youngblood

The Johns Hopkins University Applied Physics [email protected]

Agenda

•Definitions•The VV&A Processes•VV&A as Applied to the Simulation

Categories•The Key Players•Conceptual Model•Documentation•Conclusion

Definitions

What is Verification?

• The process of determining that a model or simulation implementation and its associated data accurately represents the developer's conceptual description and specifications.

• Addresses the structural integrity and the stability of the model

• Goal: Did I build the model or simulation RIGHT?

What is Validation?

• The process of determining the degree to which a model or simulation and its associated data are an accurate representation of the real world from the perspective of the intended uses of the model.

• Addresses the representational aspects of the model or simulation

• Goal: Did I build the RIGHT model or simulation?

What is Accreditation?

• The official certification that a model or simulation and its associated data are acceptable for use for a specific purpose.

• The accreditation decision is based on an accreditation assessment of the V&V evidence.

• Goal: Are the results of the M&S FIT FOR PURPOSE and USEFUL for making decisions?

The Balancing Act

Risk Resources

VV&AVV&A

Balancing the cost of knowing against the risk of assuming.

The VV&A Processes

VV&A and the Problem Solving Process

From the DOD RPG

Tailoring Guidance for VV&A : Stay Focused on the Problem

• Maintain a problem orientation• Understand the relationships between

– The problem being solved– The role of M&S in the problem– The role of VV&A in establishing M&S credibility

• If the problem is too complex, decompose it into workable units

– Ensure that you are still trying to solve the same problem

• Focus on accreditation• Ensure that the V&V evidence is clearly applicable to

the intended purpose - solving ‘this’ problem

Tailoring Guidance for VV&A : Understand the Requirements

• Define the explicit problem requirements• What specific questions are to be answered? • How will M&S be used? • What does the M&S need to do? • How good does the M&S need to be?• Define what question(s) need to be answered...• Assess the completeness, correctness, and consistency of

the M&S requirements• Define the acceptability criteria needed to assess M&S

attributes• Identify the M&S options, the VV&A credibility needs, and the

level of resources necessary to meet defined requirements

An explicit statement of the requirements is the most important aspect of cost-effective VV&A and the hardest to come by

Tailoring Guidance for VV&A : Know the Level of Credibility Required

• Credibility is Defined by the Customer - but it has a cost• Ensure that the User determines the level of credibility needed• Ensure the level of credibility is explicitly defined by the

Acceptability Criteria

• Credibility and Risk Assessment - know the limits & tolerances

• How will incorrect simulation results affect the ‘end user’ decision

• What are the costs in time and resources

• Tailor Risk Analysis to Level of Credibility Requirements• Determine how much evidence will be needed to accredit M&S• Determine the impact of NOT doing (or failing) V&V • Provide mechanisms to facilitate development of workaround

strategies and assessment of these solutions

Tailoring Guidance for VV&A: Determine How to Optimize Resources

• Not all V&V supports Accreditation to the same extent• Understand what each type of V&V evidence ‘buys’ you

relative to the cost of producing it• Determine which techniques to apply to derive required level

of credibility

• Try to avoid (re)doing it all yourself • Capitalize on existing VV&A information whenever possible• Know how to extract useful data from software V&V results

• Cooperative application of resources : use common VV&A data elements and report structure

• The VV&A Templates provides a common structure for documenting VV&A information

• Each of the Services has adopted a common database structure for their M&S Resource Repositories

VV&A as Applied to the Simulation Categories

Simulation CategoriesNew M&S Development

Any stand-alone model or simulation under development being built to address the intended purpose or purposes of the User.

Legacy Any model or simulation that was developed either in the past or for a different purpose.

FederationA system of interacting models and/or simulations, with supporting infrastructure, based on a common understanding of the objects portrayed in the system.

VV&A and New M&S Development

`

ACCREDITATION PROCESS

PROBLEM SOLVING PROCESS

EstablishObjectives

Define Problem

Accept & RecordSolution

Analyze Results

Non-M&S Methods

M&S USE PROCESS

SelectApproaches

SelectApproaches

ApplyResultsApply

Results

Repository

Executeand

Prepare Results

yes

noMakeAccreditation

Decision

Develop New M&SDefineM&S

Rqmts

PlanApproach

M&S Method M&S DEVELOPMENT/PREPARATION PROCESS

Refine M&S

Rqmts

Refine M&S

Rqmts

Plan M&S

Develop-ment

Plan M&S

Develop-ment

Develop Con-

ceptual Model

Develop Con-

ceptual Model

Imple-ment &

Test

Imple-ment &

Test

Develop Design

Develop Design

Collect and Evaluate Accreditation InformationCollect and Evaluate Accreditation Information

PerformAccreditationAssessment

PerformAccreditationAssessment

Develop Accreditation

Plan

Develop Accreditation

Plan

V&V PROCESS

Verify DesignVerify Design

Validate Concep

-tual Model

Validate Concep

-tual Model

Verify Imple-ment-ation

Verify Imple-ment-ation

Validate Results

Validate Results

Verify Rqmts

Verify Rqmts

Develop V&V Plan

Develop V&V Plan

Prepare M&S for

Use

Prepare M&S for

Use

Challenge Issues that Impact VV&A Implementation

• The lack of a well defined referent• Determining how to use and when to

use Subject Matter Experts• The lack of insight into the M&S• The lack of M&S stability• Starting the V&V/A process “late”• Keeping the second “V” in V&V

VV&A and Legacy M&S

Is There Sufficient Info to Assess the

M&S?

NO

Refine RequirementsAnd Verify

Obtain Needed Information and Verify

NO

YES

NO

Plan/Conduct Accreditation Assessment

Plan M&S Modification

Modify and Verify

Use As-IsUse As- Is or Modify?

Reject M&S

Are the Requirements

Adequate?

Validate

Prepare M&Sfor Use

Issue Accreditation

Decision

AA

UserAA

Define Requirements

UserAA

Select Legacy M&S

AA

AA AAVV

User

User

UserProp

UserAA, VV

VVUser

Prop. UserDev, VV

PropDev

Dev, VVProp

Is the Infoon M&S Capability

Adequate?

Can the M&S be Used?

Modify

V&V as Needed

VV

NO

YES

Prop, DevAA, VV

[ AA ] Accreditation Agent[ User ] User[ Dev ] Developer [ VV ] V&V Agent[ Prop ] M&S Proponent

[ AA ] Accreditation Agent [ User ] User[ Dev ] Developer [ VV ] V&V Agent[ Prop ] M&S Proponent

VVYES YES

Advantages of Using Legacy M&S• Starting with a legacy simulation may be more expedient, requiring

less time and fewer resources than a new development

• The experience of previous developers and users may be leveraged to establish a knowledge base that can provide guidance and support training

• Testing and VV&A histories can provide evidence of simulation capabilities and limitations allowing the current effort to focus on high risk areas

• A legacy simulation with a good reputation for providing credible results in similar applications can increase the simulation’s credibility (i.e., the User’s confidence in the simulation’s ability to address the current situation) due to

– the demonstrated ability to address similar requirements

– the demonstrated capabilities of the existing simulation

– the direct experiences of previous users who successfully applied the simulation to related problems

Disadvantages of Using Legacy M&S

• The simulation was developed to address different requirements

• Unexpected and undesirable side effects may occur during execution of the code

• The simulation comes with specific hardware and software, which may be obsolete

• The simulation comes with specific data needs, however the data to fulfill those needs may no longer be authoritative or available

• Information about the simulation and its previous usage may be incomplete or inconsistent

• Participants (e.g., Accreditation Agent, V&V Agent) may need time up front to acquire knowledge about the simulation

What Can Help Reduce Legacy V&V Cost

• Documentation that can directly support the accreditation assessment can reduce the burden of an extensive discovery effort

• Documentation that completely and accurately describes simulation capabilities and use history can reduce the discovery and training costs

• A simulation under configuration control with an established user community that can provide necessary information can reduce the support and discovery costs

• Participants familiar with the simulation can reduce the need for extensive training

Scope of the Distributed M&S Problem

Distributed M&S:Technical Interoperability

From “HLA and Beyond: Interoperability Challenges” by Dahmann, Salisbury, Barry, Turrell, and Blemberg (99F-SIW-073)

• Characterized by the ability of federates to physically connect and exchange data

• Involves the use of common standards, compatible interfaces and coordinated data structures

• Elements of technical interoperability– Hardware compatibility– Standards compatibility– Time management coordination– Coordinated use of Runtime Infrastructure

(RTI) services– Security issues

Distributed M&S: Substantive Interoperability Issues

Simulation Interoperability focuses on the capability of federates, when connected, to provide adequate, accurate & consistent simulated representations that adhere to the principles of “fair fight” & address the mission objectives.

•Elements of Substantive Interoperability• Logical interaction between entities modeled in

different federates• Temporal resolution• Spatial resolution • Coherent relationships between the

components of the physical environment

Top Level View of the VV&A Overlay to the FEDEP (IEEE 1516.4)

FEDEP

VV&A Overlay to the FEDEP

FEDEP INFORMATION & PRODUCTS

Plan,Integrate

& TestFederation

Plan,Integrate

& TestFederation

Step 5

Validate &Accept

Federation

Validate &Accept

Federation

Phase 5

•Validate the integrated federation results against the Federation Acceptability Criteria and against the Federation Referent.

•Formulate federation acceptance/ accreditation recommen-dations.

ExecuteFederation& PrepareOutputs

ExecuteFederation& PrepareOutputs

Step 6

V&VFederation

Output

V&VFederation

Output

Phase 6

•Verify the federation outputs internally.

•Validate federation output against the Federation Acceptability Criteria and against the Federation Referent.

DefineFederationObjectives

DefineFederationObjectives

Verify Federation Objectives


Phase 1

•Verify the Federation Objectives with the User /Sponsor.

•Define the Federation Acceptability Criteria.

•Assemble the Federation Referent.

•Plan the VV&A activities.

Step 1

PerformConceptual

Analysis

PerformConceptual

Analysis

V&VFederationConceptual

Model

V&VFederationConceptual

Model

Phase 2

•Verify the Federation Conceptual Model internally.

•Validate the Federation Conceptual Model against the Federation Referent and against the Federation Acceptability Criteria.

Step 2

DesignFederation

DesignFederation

VerifyFederation

Design

VerifyFederation

Design

Phase 3

•Verify the Federation Design internally.

•Verify the Federation Design against the Federation Conceptual Model.

Step 3

DevelopFederation

DevelopFederation

VerifyFederation

DevelopmentProducts

VerifyFederation

DevelopmentProducts

Phase 4

•Verify the federation development products internally.

•Verify the federation development products against the Federation Conceptual Model.

Step 4

AnalyzeData &

EvaluateResults

AnalyzeData &

EvaluateResults

ConsolidateFederation

VV&AProducts

ConsolidateFederation

VV&AProducts

Phase 7

•Collect all VV&A products and lessons learned.

•Assemble them into a VV&A package to support federation reuse.

Step 7

Tasks Associated with each VV&A Overlay Phase

Verify Federation

Design

Verify Federation

Design

3.0

Support Selecting Federates

Support Preparing Federation

Design

Contribute to Verifying

Federation Design

Support Preparing Federation

Development & Execution

Plan



1.0

Support Identifying

User/Sponsor Needs

Plan Accreditation

Activities


Federation Objectives

Support Developing Federation Objectives

Assemble Federation Referent

Define Federation

Acceptability Criteria

Plan V&V Activities

V&V Federation Conceptual

Model

V&V Federation Conceptual

Model2.0

Support Developing Federation Scenarios


Federation Scenarios


Federation Requirements

Support Developing Federation

Requirements

Support Developing Federation Conceptual

ModelContribute to

Verifying Federation Conceptual

ModelValidate

Federation Conceptual

Model

Validate & Accept

Federation

Validate & Accept

Federation

5.0

Support Planning

Federation Execution

Support Integrating Federation


Integrated Federation

Support Testing

Federation

Perform Acceptance Assessment

Validate Integrated Federation

Results

V&V Federation

Output

V&V Federation

Output

6.0

Support Executing Federation

Contribute to Verifying Raw Execution and

Derived Output

Validate Federation

Outputs

Consolidate Federation

VV&A Products

Consolidate Federation

VV&A Products

7.0

Support Analyzing

Data

Prepare Federation

VV&A Products for

Reuse

V&V Federation Data Sets

Verify Federation

Development Products

Verify Federation

Development Products

4.0

Support Developing

FOM

Contribute to Verifying FOM

Support Establishing Federation

Agreements


Federation Agreements


Federation Infrastructure

Support Implementing

Federate DesignsSupport

Implementing Federation

Infrastructure

The Key Players

User

• The User wants to use the simulation to provide an answer or solve a problem; he is concerned that the simulation can provide credible answers.

• The User defines the objectives and the requirements, scenarios and use cases, and generally serves as the subject matter expert (SME) for issues in the problem and user domains.

• Ultimately the User is the one who decides whether the simulation is credible enough to use.

Accreditation Agent

• The Accreditation Agent prepares for and conducts a cost-effective accreditation assessment that results in a logical, sufficient, and fully justified accreditation recommendation to the User.

• The Accreditation Agent assists the User with activities that help establish the scope of the problem to be addressed.

• The Accreditation Agent serves as the User’s advocate throughout the M&S development process.

Accreditation Agent Challenges

• Ensuring the definition of the intended use

• Using existing V&V documentation• Coping with configuration

management difficulties• Locating appropriate Subject Matter

Experts• Overcoming delay in appointment of

the accreditation agent• Obtaining needed resources• Communicating the results of the

accreditation assessment

V&V Agent

• The V&V Agent plans and performs the verification and validation (V&V) activities

• The V&V Agent ensures that sufficient evidence is gathered to demonstrate that the simulation meets the stated requirements in terms of their associated measures and acceptability criteria.

V&V Agent Challenges• Obtaining well-defined accreditation

information needs• Dealing with missing documentation• Establishing V&V support system and

infrastructure• Finding adequate resources• Selecting the right people• Managing the V&V effort• Leveraging configuration management

resources• Tracking and reporting V&V effort progress

Conceptual Model

Definition

“The conceptual model is a simulation developer’s way of translating modeling requirements into a detailed design framework, from which the software, hardware, networks, and systems/equipment that will make up the simulation can be built, modified, or assembled.”

from SIW Paper 00F-SIW-019, “Simulation Conceptual Model

Development Issues and Implications for Reuse of SimulationComponents” by Dr. Dale Pace

Why Conceptual Models?

“The biggest indication that Trespasser had game design problems was the fact that it never had a proper design spec…. Trespasser started and finished weak in the game design, and this affected every other part of the project.” – Richard Wyckoff,

“Postmortem: DreamWorks Interactive’s Trespasser” Gamasutra, May 14, 1999.

From presentation 03F-SIW-080.ppt by Gustavson, Turrell, Zimmerman at Fall 2003 SIW

http://www.game-over.net/review/october/trespasser/Screen0.JPG

Why Conceptual Models?

“We never had a proper design document, which meant that we generated a lot of code and art that we later had to scrap. What’s worse, because we didn’t have a detailed outline of what we were trying to build, we had no way to measure our progress (or lack thereof) accurately. We only realized that we were in trouble when it became glaringly obvious. If we’d been about the design rigorous up front, we would have known that we were slipping much sooner.”

– Brian Upton, “Postmortem: Red Storm's Rainbow Six” Gamasutra, January 21, 2000.

From presentation 03F-SIW-080.ppt by Gustavson, Turrell, Zimmerman at Fall 2003 SIW

http://www.game-over.net/shot.php3?page=reviews&id=317&number=1

Conceptual Model Components

(1) Simulation Context

Authoritative Information re: relevant entities/processes, data,

algorithms, assumptions, behaviors, etc.

Sets constraints/bounds on the Simulation Concept

Simulation Concept

(2) Mission Space -- Representation Aspect

Simulation Elements

Entities/processes represented (tasks, actions, behaviors, etc.) by

assumptions, algorithms, data, and relationships (architecture)

(3) Simulation Space

Operational/functional capabilities

RequirementsRequirements

Constraints

Conceptual Model

SpecificationsSpecifications

Benefits of a Conceptual Model

• A good conceptual model can improve requirements

• Good requirements are important because

– Faulty requirements cause half of software errors

– Late error detection/correction is much more expensive than early error detection/correction

• A good conceptual model allows early

– Estimation of simulation fidelity

– Development of validation sampling methodology

– Assessment of simulation validity for the intended use

– Determination of compatibility with other M&S/tools

Conceptual Model Documentation• Conceptual Model Portion Identification• Principal Simulation Developer POCs• Requirements and Purpose• Overview• General Assumptions• Identification of Possible States, Tasks, Actions,

and Behaviors, Relationships and Interactions, Events, and Parameters and Factors for Entities and Processes being described

• Identification of Algorithms• Simulation Development Plans• Summary and Synopsis

Documentation

Documentation Philosophy

• Organize information according to a standard outline– Rationale

• Eases the comparison of data with accreditation requirements

• Facilitates V&V data accumulation for future use• Reduces costs of multiple accreditations over time

– Specific outlines vary with type of data element

• Structure V&V results to facilitate comparison with M&S requirements

– Include description of how the results impact m&s use– State newly discovered discrepancies as assumptions,

limitations on model use, or as errors– Identify the range of applicability for all results (particularly

regarding any limitations or errors)– Ensure results are linked to the applicable M&S version

• Configuration Management

MIL-STD 3022: VV&A Documentation Templates

Accreditation Plan V&V Plan V&V Report Accreditation Report

Executive Summary Executive Summary Executive Summary Executive Summary

1 Problem Statement 1 Problem Statement 1 Problem Statement 1 Problem Statement

2 M&S Requirements and Acceptability Criteria




3 M&S Assumptions, Capabilities, Limitations & Risks/Impacts




4 Accreditation Methodology 4 V&V Methodology 4 V&V Task Analysis 4 Accreditation Assessment

5 Accreditation Issues 5 V&V Issues 5 V&V Recommendations 5 Accreditation Recommendations

6 Key Participants 6 Key Participants 6 Key Participants 6 Key Participants

7 Planned Accreditation Resources

7 Planned V&V Resources 7 Actual V&V Resources 7 Actual Accreditation Resources

8 V&V Lessons Learned 8 Accreditation Lessons Learned

Suggested Appendices:A M&S DescriptionB M&S Requirements Traceability MatrixC Basis of ComparisonD ReferencesE Acronyms F GlossaryG Accreditation ProgrammaticsH Distribution List

Suggested Appendices:A M&S DescriptionB M&S Requirements Traceability MatrixC Basis of Comparison D ReferencesE AcronymsF GlossaryG V&V ProgrammaticsH Distribution ListI Accreditation Plan

Suggested Appendices:A M&S DescriptionB M&S Requirements Traceability MatrixC Basis of ComparisonD ReferencesE AcronymsF GlossaryG V&V ProgrammaticsH Distribution ListI V&V PlanJ Test Information

Suggested Appendices:A M&S DescriptionB M&S Requirements Traceability MatrixC Basis of Comparison D ReferencesE AcronymsF GlossaryG Accreditation ProgrammaticsH Distribution ListI Accreditation PlanJ V&V Report

VV&A Data Archiving• VV&A Documents

– Should be archived in central location: • Defense Department level or• Program level

– Indexed in a electronic database– Possibly available on-line

• Electronic Database– Should contain summarized,

unclassified data from VV&A reports– Should be sufficient for model

comparisons and selection

VV&A data are only useful if they are documented, and the documentation is readily available to model

users.

VV&A data are only useful if they are documented, and the documentation is readily available to model

users.

Conclusion

Summary of VV&A• Cost-effective accreditation requires

– Complete problem definition– Clear application description – Explicit statements of M&S requirements and

acceptability criteria– A well-planned, tailored and focused accreditation

assessment effort • Efficient V&V to support accreditation requires

– A clearly defined application context to permit focused V&V efforts

– The use of risk to focus and tailor the V&V effort– A clear understanding of how each V&V activity

contributes to M&S credibility– A means of extracting key accreditation support

information from previous V&V (and other M&S) efforts

– An efficient means to produce, document, and archive all V&V information (from software and M&S V&V)

Simone [email protected]

(240) 228-7958

I/ITSEC Tutorial #1019 The Basics of the M&S VV&A Process

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