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Voting Methods Working Group (VMWG)

READ-ONLY SITE MATERIALS: Historical voting TWiki site (2015-2020) ARCHIVED from

Voting Methods Standard


The purpose of this guidance and standard is to enable adopters to produce correct and accurate determination of outcome of government operated elections in US government jurisdictions. This guidance and standard enables manufacturers, elections administrators (EA), elections officials (EO), elections analysts, testing and certification labs, and informs the Technical Guidelines Development Committee (TGDC) of the Election Assistance Commission (EAC) and future versions of the Voluntary Voting System Guidelines (VVSG), and other stakeholders including the general public. This guidance and standard supports Data Interoperability (DI) and data integrity, and enables EA systems to be valid to a high degree of confidence, accurate, fail-safe and cost effective.

To achieve Data Interoperability(DI), this guidance and standard enables stakeholders to architect elections administration systems where the characteristics of calculations performed are precisely known for components, sub-systems or systems, and across systems where data flows or where data is collected and analysed separately. Adoption of this standard enables DI within a jurisdiction's systems and also inter-jurisdictional data and multiple-jurisdiction data aggregation and analysis, and may also apply to testing and certification.

Status VMWG Draft NIST SP 1500-107 Voting Methods Models, Appendix G Glossary 2018 Q3-Q4 April 2018
Tabulation Process Flow Diagrams
2018 Presentation Slides - Coming Soon 2018
Presentation Slides
VM-WG Draft NIST SP 1500-107 Voting Methods Models 2018 - Coming Soon VMWG Draft NIST SP 1500-107 Voting Methods Models 2018 2018
Q2-Q3 2018 VMWG Roadmap Q2-Q3 Roadmap 2018
NIST_TGDC_Interop_Presentation_VotingMethodsWG_V5_5_20170907_Lochridge-et-al Sept. 2017 Presentation Slides 2017-09-08
NIST 1500-X Voting Methods Models Draft Outline Sept. 2017 NIST 1500-107 Voting Methods Models Draft Document, Outline 2016-09-23
DRAFT TGDCPresentation_VotingMethodsModels_V3_20160831_LML.pdf VM-WG Draft 2016 Slide Deck 2016-08-31
New: Github rep at usnistgov/VotingMethods Voting Methods Public Repository: 2016


VMWG meets periodically. Our membership is formed of experts and a variety of stakeholders including elections officials, elections administrators, manufacturers, software and service providers, ISVs, academicians, researchers, organizations and NGOs, and analysts.

Subgroups of VMWG form as needed to complete work product and deliberate as subject matter experts. Subgroups of VMWG form as needed and meet for status, deliberation, and to produce technology architecture, reference architecture, reference implementations, rapid prototypes for proof of concepts, and other work product and artifacts.

VMWG is a subgroup of NIST Interoperability. Some of our VMWG members are also participants of the other working groups developing standards, requirements recommendations and guidelines with NIST Voting and to inform the NIST Technical Guideline Development Committee (TGDC), which in turn informs the Election Assistance Commission (EAC).

The VMWG team and members participate in NIST CyberSecurity WG, Election Business Process Models WG, Testing WG and contribute to the development of other work product including standards for Cast Vote Records, Election Results Reporting, Election Logging, NIST VVSG Glossary, and more.

The standard, specifications and guidance that VMWG produces adopt or are consistent with the standards, specifications and guidance that are produced by the constellation of other working groups, and other NIST standards.

The VMWG team is primarily concerned with Voting Methods, Tabulation Methods, the Data Integrity (DI) and Data Interoperability of vote selection data sets representing ballots, and the common format for operations on vote selection data sets.

Voting Method

A voting method encompasses a set of partially ordered process steps, tabulation methods, and decision rules. Each voting method has at least one associated tabulation method and at least one election outcome decision rule set consisting of at least one decision rule. Executing the appropriate tabulation method and election contest decision rule set is in the scope of the voting method.

Tabulation Method

A tabulation method is a set of partially ordered process steps and operations for performing counting, accumulation, aggregation and other data and math operations on vote selection data sets. Each tabulation method supports at least one tabulation scenario.

Data and math operations include but are not limited to: vote counting, reporting of numeric results, reporting of statistics, or other election ballot marks and contest counting or tally data operations. Tabulation counting and data operations may be performed for a variety of purposes, or use cases, including but not limited to audits, end-to-end verification, logic and accuracy testing (L&A testing).

Tabulation Scenario

A situation and sequence of events or activities intended by Elections Administrators to be sufficient to achieve a tabulation goal.

A tabulation scenario is a situation and sequence of events, steps in process, and tabulation state changes. Sets of ballots, in the form of NIST 1500-103 Cast Vote Record Cast Vote Record data sets, are operated upon according to the defined process of tabulation being executed, with the objective of producing an output count and related statistics, and other reporting for a particular instance of tabulation.

A tabulation scenario may be intended to count only a subset of the total number of ballots needed to count for an election contest result that is determined and output by a Voting Method. Examples of tabulation scenarios include but are not limited to configuration or logic and accuracy testing, batch, precinct tabulation, central tabulation, county or statewide ‘rollups’ or aggregations, recounts, and audits. Tabulation scenarios are also use cases for the voting methods that execute the applicable set of one or more tabulation methods.

VMWG ongoing activity includes, and is not limited to rapid prototyping and producing work product as follows.

  • Rigorously and precisely defined models of voting schemes, voting methods, or modules where counting, tabulation, mathematical evaluation, or common operations on vote data sets are performed in Elections Administration (EA) systems.
  • A prototype process for knowledge acquisition and representation of EA counting and tabulation methods from the rules and guidelines for administering elections. EA processes are typically specified in written legislation, statute, rules, and guidelines, or Request For Proposals (RFP) produced by Elections Officials (EO). English, or any spoken and written language is naturally less precise than a mathematical specification. Specifically, this process extracts the specification of counting and tabulation methods from plain language legislation and rules and represents the counting and tabulation methods as mathematical models and process models.
  • Use Cases

    Use cases include auditing, aggregation & roll-up, end-to-end verification, evidence procedures, capacity planning, testing, certification testing, security, information privacy, logging & tracing, common vote selection data set operations, legislative specification, Election Official's specifications for RFIs and RFPs.

  • Reference Architecture, Reference Mechanized Voting Method Models, Tools and examples, reference implmentation of verifiable tabulation and voting methods engines.

  • Precise specifications for optional and voluntary use in Legislation and Elections Officials Rules and Guidelines, currently in draft as NIST SP 1500-107.

Applications of this Voting Methods Models specification are consistent with NIST VVSG Interoperability guidelines or requirements and Common Data Format (CDF) specifications and requirements produced by other NIST Voting or VVSG groups, including Cybersecurity.

Executive Summary

The NIST Voting Models Working Group (VMWG) produces this Voting Methods Models Standard to enable data interoperability and data integrity in the architecture of elections administration (EA) systems and for application to testing and certification of EA systems. This standard seeks to enable stakeholders to architect or analyze elections administration systems where the characteristics of calculations performed are precisely known for components, sub-systems or systems, and across systems where data flows or where data is collected and analyzed separately. Adoption of this standard enables Data Interoperability within a jurisdiction's systems and also inter-jurisdictional data and multiple-jurisdiction data aggregation and analysis, and may also be applied to testing and certification. It provides a set of rigorously and precisely defined mathematical models of voting schemes, voting methods, or modules where counting, tabulation, mathematical evaluation, or common operations on vote data sets are performed in Elections Administration (EA) systems, and provides a process for knowledge acquisition and representation of EA counting and tabulation methods from the rules and guidelines for administering elections. Data Interoperability (DI) is complementary to Data Interchange or Transport Interoperability and both enable EA systems to be, valid to a high degree of confidence, accurate, fail-safe, and cost effective.


This publication describes a standard for precise specification of elections administration voting methods and mathematical evaluation modules, including counting and tabulation. This specification is a set of voting methods elements where each element is a voting method mathematical model, with its corresponding unique identifier and description. Each element is a precise definition which can be referenced without ambiguity, reused, and understood by a variety of stakeholders including legislators, elections officials, analysts, systems and software manufacturers, and those performing testing and certification. Adoption of this standard supports vote selection Data Interoperability through a Common Data Format. This specification includes a reference implementation of select voting methods and description of the methodology for knowledge acquisition and representation for domain modeling of counting and tabulation methods.

NIST SP 1500-107, initial version 1.0 is expected to be complete for VVSG 2.0in the following parts.

● Set of common format modules for operations on vote selection data sets, representing the plain language algorithmic definitions in U.S. elections legislation, rules, guidelines, for voting methods, as precise mathematical logic specifications, each with description and unique identifier, for the subset of all voting methods that are complete in each specification version.

● UML model of voting methods modules domain, mapped to the Elections Modeling business process model framework. The Elections Modeling sub-group of NIST Voting, Interoperability, is a peer to VMWG, and may be found here: Election Modeling

● Use Cases

● Reference Architecture

● Reference implementation including a set of packaged tools and examples for validating modules in a particular configuration or use case

See also the Sept. 2017 Presentation slides in the table of Status documents (above), for a current overview.

See also: *

*We're in the process of updating our github repository


VM-WG Co-Chair & Editor: Lauren Massa Lochridge

NIST Co-Chair: John P. Wack

VM-WG Co-Chair for Auditability and Risk Management: Philp B. Stark

VMWG Membership

  • Lauren Massa Lochridge, Working Group Co-Chair
  • John P. Wack, NIST Co-Chair
  • Philip B. Stark, Co-Chair for Auditability and Risk Management, Associate Dean, Division of Mathematical and Physical Sciences |Professor | Dept of Statistics | UC Berkeley
  • Herb Deutsch, ES&S
  • Joseph Kiniry, Galois and Free & Fair
  • Carsten Schurmann, IT University of Copenhagen
  • Kimball Brace, Election Data Services, Inc.
  • Kenneth Bennett, Los Angeles County, CA
  • David Buerger, Elections Specialist Wisconsin Government Accountability Board, WI
  • John Dziurlaj, Office of Secretary of State, OH
  • Barbara Simons, Former President ACM, Former EAC Board of Advisors
  • Olivier Pereira, Catholic Universityof Leuven
  • Peter Ryan, University of Luxembourg
  • Chris Jerdonek, Elections Commissioner & President of the City & County of San Francisco Elections Commission, CA
  • Tammy Patrick, Senior Advisor to the Democracy Project, Bipartisan Policy Center
  • Don Rehill, Dir. Elections Research and Vote Tabulation, Associated Press
  • Benjamin Rice, Dominion Voting
  • Steve Schneider, Asooc. Dean, Director, Surrey Centre for Cyber Security University of Surrey
  • Beth Ann Surber, West Virginia, Office of Secretary of State, WV
  • Chris Jackson, Ipsos Public Affairs
  • Arthur Keller, Computer Engineering department, University of California, Baskin School of Engineering
  • Lynn Garland, Independent
  • Michael Greenman, VP of Emerging Technology & Corporate Development, SOE, a Scytl company
  • Neal McBurnett, ElectionAudits
  • Art Griesser, Prometheus Computing
  • Vanessa Teague, University of Melbourne, Dept. of Computing and Information Systems
  • John Rose, Maxim Consulting, Inc., a Scytl Company
  • Ron Rivest, MIT
  • George Gilbert, Former BOE Director, NC
  • Chris Hughes, FairVote
  • David Wallick, Votem
  • Observers

  • Poorvi Vora, GWU
  • Sarah Whitt, Wisconsin Elections Division
  • David Becker, Center for Elections Innovation & Research
  • Jared Marcotte, Open Source Advocate, Developer, and UX Strategist
  • Justin Moore, Google, Voting Information Project
  • Rob Richie, FairVote
  • Jameson A. Quinn, Harvard

    *Note: Affiliations where given are for the purpose of identification only.


Voting Methods Public Github Repository: [under construction] VM-WG Public Git Repo

Email List

Email: voting-methods [at] (voting-methods[at]list[dot]nist[dot]gov)

To join the list or find more information about list policies and related procedures, please visit the VVSG Working Group Lists page.



Policies and Procedures:

Reference Architecture:

Work To-Date:

Technology Roadmap:



Previous Attachment Files to the twiki can be found on the GitHub site)

Voting TWiki Archive (2015-2020): read-only, archived wiki site, National Institute of Standards and Technology (NIST)


This page, and related pages, represent archived materials (pages, documents, links, and content) that were produced and/or provided by members of public working groups engaged in collaborative activities to support the development of the Voluntary Voting System Guidelines (VVSG) 2.0. These TWiki activities began in 2015 and continued until early 2020. During that time period, this content was hosted on a Voting TWiki site. That TWiki site was decommissioned in 2020 due to technology migration needs. The TWiki activities that generated this content ceased to operate actively through the TWiki at the time the draft VVSG 2.0 was released, in February of 2020. The historical pages and documents produced there have been archived now in read-only, static form.

  • The archived materials of this TWiki (including pages, documents, links, content) are provided for historical purposes only.
  • They are not actively maintained.
  • They are provided "as is" as a public service.
  • They represent the "work in progress" efforts of a community of volunteer members of public working groups collaborating from late 2015 to February of 2020.
  • These archived materials do not necessarily represent official or peer-reviewed NIST documents nor do they necessarily represent official views or statements of NIST.
  • Unless otherwise stated these materials should be treated as historical, pre-decisional, artifacts of public working group activities only.
  • NIST does not warrant or make any representations regarding the correctness, accuracy, reliability or usefulness of the archived materials.


This wiki was a collaborative website. NIST does not necessarily endorse the views expressed, or concur with the facts presented on these archived TWiki materials. Further, NIST does not endorse any commercial products that may be mentioned in these materials. Archived material on this TWiki site is made available to interested parties for informational and research purposes. Materials were contributed by Participants with the understanding that all contributed material would be publicly available.  Contributions were made by Participants with the understanding that that no copyright or patent right shall be deemed to have been waived by such contribution or disclosure. Any data or information provided is for illustrative purposes only, and does not imply a validation of results by NIST. By selecting external links, users of these materials will be leaving NIST webspace. Links to other websites were provided because they may have information that would be of interest to readers of this TWiki. No inferences should be drawn on account of other sites being referenced, or not referenced, from this page or these materials. There may be other websites or references that are more appropriate for a particular reader's purpose.


Created August 28, 2020, Updated February 5, 2021