NISTIR 7082

Proficiency Test Policy and Plan 

(for State Weights & Measures 

Laboratories)

Jeff C. Gust 

Quametec Corporation 

(under NIST contract) 

Georgia L. Harris 

Laboratory Metrology Group 

Weights and Measures Division 

National Institute of Standards and Technology

Technology Administration 

U.S. Department of Commerce 

NISTIR 7082

Proficiency Test Policy and Plan 

(for State Weights & Measures 

Laboratories)

Jeff C. Gust 

Quametec Corporation 

(under NIST contract) 

Georgia L. Harris 

Laboratory Metrology Group 

Weights and Measures Division 

Technology Services 

January 2004 

U.S. DEPARTMENT OF COMMERCE

Donald L. Evans, Secretary

TECHNOLOGY ADMINISTRATION

Phillip J. Bond, Under Secretary of Commerce for Technology

NATIONAL INSTITUTE OF STANDARDS AND 

TECHNOLOGY

Arden L. Bement, Jr., Director 

Proficiency Test Policy and Plan 

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Table Of Contents 

Table Of Contents............................................................................................................... 1 

Preface................................................................................................................................. 3 

Introduction......................................................................................................................... 5 

PT Requirements................................................................................................................. 7 

1. Policy .......................................................................................................................... 9 

2. Proficiency Test (PT)/ Interlaboratory Comparison (ILC) Plan............................... 11 
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Preface 

This document has been prepared by Jeff C. Gust (Quametec Corp., under contract) in 

collaboration with NIST Weights and Measures Division staff as a first step in the 

process of enabling State weights and measures laboratories to comply with criteria for 

proficiency testing as noted in NIST Handbook 143 and as needed for accreditation 

programs. This project is intended to align NIST policies to international mutual 

recognition arrangement requirements, and to ensure that proficiency tests developed 

within this program meet all international requirements for design, development, 

execution, analysis and reporting of proficiency tests. 

The following individuals participated in the development and/or review of this 

document: 

Jeff C. Gust, Quametec Corp. 

Georgia L. Harris, NIST/WMD 

G. Diane Lee, NIST/WMD 

Val Miller, NIST/WMD 

Doug Faison, NIST/NVLAP 

Ross Andersen, NY 

Richard Cote, NH 

Mike Dynia, CT 

L.F. Eason, NC 

Ken Fraley, OK 

Kelley Larson, AZ 

Steve Sumner, NM 
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Proficiency Test Policy and Plan 

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Introduction 

This proficiency testing policy and plan is designed to assist the States and Regional 

Measurement Assurance Program (RMAP) groups in identifying the minimum level of 

proficiency testing needed on an ongoing basis to comply with international expectations 

as described in the PT Requirements section of this document. In realizing compliance to 

this policy, some of the Proficiency Tests (PTs) and Interlaboratory Comparisons (ILCs) 

will be conducted through the RMAP groups and some, by necessity, will have to be 

coordinated on a national basis. This plan addresses these different coordination needs. 

While the NIST Weights and Measures Division (WMD) does not operate as a formal 

Accreditation Body, WMD is responsible for the Measurement Assurance Recognition 

program. This program is documented in NIST Handbook 143 (2003). WMD issues 

Certificates of Measurement Traceability to support commerce and measurements made 

for legal metrology. This policy and plan is consistent with international guidelines set 

forth by the International Laboratory Accreditation Cooperation (ILAC). It also 

supplements PT/ILC requirements of the General Technical Requirements for Calibration 

Labs in NIST Handbook 143, which are based on ISO/IEC 17025, section 5.9. 

As part of the State Laboratory Program (SLP) described in NIST Handbook 143, the 

WMD is responsible for Regional Measurement Assurance Programs (RMAPs) where 

Metrologists from State legal metrology laboratories in six regions are required to attend 

annual training and participate in proficiency testing in planned measurement areas for 

which they will seek WMD recognition. State metrology laboratories may also seek 

accreditation from recognized accreditation bodies. The results of the proficiency testing 

from the RMAPs may be used to meet accreditation requirements for proficiency testing 

in addition to meeting WMD requirements. 

The six regions are as follows: 

1. Northeastern Measurement Assurance Program (NEMAP) 

2. Southeastern Measurement Assurance Program (SEMAP) 

3. Southwestern Assurance Program (SWAP) 

4. Mid-America Measurement Assurance Program (MidMAP) 

5. Western Regional Assurance Program (WRAP) 

6. Caribbean Measurement Assurance Program (CaMAP) 

Most PTs/ILCs are coordinated through and by members of these regional groups. Some 

PTs/ILCs are coordinated on a national basis. 

Previous WMD activities related to developing PT “plans” have included a draft schedule 

of proficiency testing in the form of interlaboratory comparisons and round robins. This 

document is intended to align WMD policies and procedures with the most recent ILAC 
Proficiency Test Policy and Plan 

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documents and to make planning a more formal part of an ongoing program for PTs/ILCs 

within the Weights and Measures Division, Laboratory Metrology Group. 
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PT Requirements 

In order for an accreditation body to sign a Mutual Recognition Arrangement (MRA) with 

the International Laboratory Accreditation Cooperation (ILAC) or a regional accreditation 

cooperation such as the Asia Pacific Laboratory Co-operation (APLAC), the accreditation 

body must develop a quality system that meets the criteria for recognition. ILAC provides 

the procedure ILAC P1:2003 “ILAC Mutual Recognition Arrangement Requirements for 

Evaluation of Accreditation Bodies by ILAC Recognized Regional Co-operations” that sets 

forth the requirements for entry into an the ILAC MRA. 

ILAC P1:2003, Section 5, Criteria for Evaluation, specifies requirements of proficiency 

testing activities that the accreditation body must require of laboratories that they accredit. 

Section 5.3 recommends that at a minimum, laboratories successfully participate in at least 

one proficiency test prior to gaining accreditation and one proficiency test relating to each 

“Major Discipline” [metrology area], and “Major sub-area” [branch and/or service], of a 

laboratory’s scope of accreditation during a four-year period. 

Regional organizations such as APLAC have adopted the P1:2003 recommendation in 

APLAC MR0001 “Procedures for Establishing and Maintaining Mutual Recognition 

Agreements Between Accreditation Bodies.” Section 3.3 of this document requires 

accreditation bodies to specify that accredited laboratories participate in a minimum of one 

proficiency test prior to accreditation and one proficiency test for each “Major Discipline” 

[metrology area], and “Major sub-area” [branch and/or service], of a laboratory’s scope of 

accreditation at least every four years. 

Some accreditation bodies such as the American Association for Laboratory Accreditation 

(A2LA) have added to the ILAC recommendation by requiring laboratories to participate in a 

minimum of two proficiency tests per year and to cover their laboratory technical scope 

every four years (Document - A2LA Proficiency Testing Requirements). 

The NIST WMD is not a formal accreditation body following ISO Guide 58 and does not 

enter into national or international agreements for acceptance and reciprocity as noted earlier. 

However, one goal of the NIST WMD is to encourage/ensure the adoption of uniform 

measurement practices in the State Weights and Measures laboratories that are used 

internationally in calibration and metrology laboratories. NIST Handbook 143, Program 

Handbook (2003) contains the requirements for participation in a measurement assurance 

program that are based on ISO/IEC 17025. The objective of the plan described in this 

document is to assist State laboratories to comply with ISO/IEC 17025 and the ILAC P1 

criteria for demonstrating proficiency. 
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Summary of PT Requirements from Accreditation Cooperation’s and Accreditation Bodies 

Organization Reference Document PT Requirement 

ILAC P1:2003, 5.3 Accreditation Body must specify 

minimum PT requirements 

Recommendation (not requirement): 

1 PT prior to obtaining accreditation 

1 PT for each major sub-area during a 

four year period 

APLAC MR-001, 3.3 1 PT prior to obtaining accreditation 

1 PT for each major sub-area during a 

four year period 

NVLAP Handbook 150 (2001 Edition) 

3.3 

No documented minimum participation 

requirements 

NVLAP Handbook 150-2C (technical 

guide for time and frequency 

measurements), 1.7.2 

1 PT per year per field 

NVLAP Handbook 150-2E 

(technical guide for optical 

radiation measurements), 1.7.2 

1 PT per year per field 

NVLAP Handbook 150-2 

(additional technical guides for 

measurement parameters are 

being developed) 

1 PT per year per field 

A2LA A2LA Proficiency Testing 

Requirements (1/2001), III 

(Calibration) 

1 PT before accreditation is granted 

2 tests per year, scope of calibration 

covered in four year period 
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1. Policy 

1.1 Proficiency Testing (PT) And Interlaboratory Comparisons (ILC) 

Proficiency tests (PTs) and interlaboratory comparisons (ILCs) are effective tools for 

a laboratory to objectively validate their measurement capability. NIST Handbook 

143 (2003) recommends the use of proficiency testing and interlaboratory 

comparisons in Section 5.9 as one of the required methods for assuring the quality of 

test and calibration results and also in Section 5.4.5.2 as a means of verifying test and 

calibration methods.

1.2 PT/ILC Requirements For Laboratories Seeking Recognition To NIST 

Handbook 143 (2003) 

Before a laboratory is granted recognition to NIST Handbook 143, the laboratory 

must participate in at least one PT/ILC that has been coordinated by a RMAP or by 

NIST WMD, or by a NIST WMD approved PT/ILC provider for each major 

measurement area for which recognition is sought. 

1.3 PT/ILC Requirements For Laboratories To Maintain Recognition To NIST 

Handbook 143 

In order to maintain recognition status to NIST Handbook 143, laboratories must 

participate in PTs/ILCs coordinated by a RMAP, NIST WMD, or by a NIST WMD 

approved PT/ILC provider as required by the NIST Handbook 143 (2003), PT/ILC 

schedule. 

Additionally, laboratories must participate in at least one PT/ILC for each service 

area included in the laboratory’s scope of recognition during a four-year period. 

Only the metrologist who has performed a particular test has demonstrated 

proficiency. The laboratory manager shall strive to ensure that all staff authorized to 

perform a particular type of measurement participates in proficiency tests when 

offered. In conducting proficiency tests, it is recognized that the participant is 

evaluated in conjunction with the laboratory facility, equipment, standards, and 

operations as the metrologist cannot be evaluated independent from the resources 

used to perform the PT/ILC. 
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Major Metrology Areas, Branches and Services 

The BIPM Key Comparison Database (KCDB) uses the Metrology 

Area/Branch/Service taxonomy for delineating measurement areas and types of 

calibration services. Other taxonomy is in use such as major discipline and major 

sub-area. The table listed below considers the BIPM nomenclature and the 

Recognition parameters listed in NIST Handbook 143, 2003. 

Proficiency Testing Frequency Requirements 

Metrology Area/Branch 

(Discipline, Parameter)

Service (Major Sub-Area, 

Scope/Range/Application)

Mass

Echelon I 

Echelon II 

Echelon III 

Mass, Fluid Flow (Volume) Echelon I Gravimetric 

Large Volume (provers) 

Small Volume (glassware) 

Echelon II Volumetric 

Large Volume Transfer 

Small Volume Transfer 

Length, Dimensional, Linear 

Length Rulers 

Length Tape (Bench or Tape to Tape) 

Temperature E.g.: Liquid-In-Glass Thermometers, RTD’s, 

SPRT’s, Thermistors, Thermocouples 

Echelon I 

Echelon II 

Echelon III 

Echelon IV 

Echelon V 

Hydrometers

Tuning Forks

Time Interval Stop Watches, Timing Devices 

Hygrometer/Relative Humidity 

Grain Moisture

NOTE: A successful completion of a PT/ILC in one service area does not imply proficiency 

in another, even within the same metrology area/branch and/or range. 
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2. Proficiency Test (PT)/ Interlaboratory Comparison (ILC) Plan 

2.1 PT/ILC Plan 

The information presented below provides guidance for planning PT/ILC activities in 

order to meet the policy requirements of this document. The level of organization 

and frequency of PTs/ILCs suggested is based on: 

2.1.1 The number of laboratories with the measurement capabilities for the 

specific metrology area. (i.e., For common measurements, several 

RMAPs may have to organize PTs/ILCs in the same metrology area in 

order to allow all, or have enough, laboratories to participate. For less 

common measurements, NIST (or individual participants) may need to 

coordinate a PT/ILC on a national basis in order to have enough 

participants. 

2.1.2 The number measurements made within a specific metrology area will 

be considered. Since nearly 90 % of the State Laboratory Program 

workload is mass calibration, more PTs/ILCs are required in mass than 

in a discipline such as length, which accounts for less than 1 % of the 

laboratory workload. This means that a greater frequency may be 

required for some parameters than two years. 

2.1.3 The historic stability of the standards used and tested within a specific 

metrology area will be considered. Length standards have been shown 

to be much more stable than mass standards. Therefore, fewer length 

PTs/ILCs are required for length calibration than for mass calibration 

in order to provide adequate demonstration of a laboratory’s 

measurement proficiency over time and the full four-year period will 

be used. 

2.1.4 The cost and logistics of the PT/ILC will be considered. For example, 

large volume PTs/ILCs that require the movement of a large trailer 

mounted prover through regions need to be coordinated by NIST. The 

frequency of this type of PT/ILC is also limited by cost of the standard 

(it is impractical to purchase multiple standards) and the time it takes 

to circulate the standard to all laboratories within each region. 

2.1.5 While the minimum requirements only dictate that the laboratories 

participate in one PT/ILC per major sub-area of their scope of 

recognition every four years, it is desirable to participate in PT/ILC 

activities for each specific metrology area and test method that the 

laboratory employs. The long range plan of participant laboratories, 

RMAPs and WMD should include plans to eventually develop 
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PT/ILCs for each specific metrology area and test method as it is 

economically and logistically feasible. 

2.1.6 The scopes of recognition (ranges) selected within each metrology 

area and service needs to be considered and should vary from test to 

test. For example, the range of 20 kg to 2 kg may be selected one year 

and the range 1 kg to 1 mg may be selected in another. Single weights 

and/or sets may be considered. 

2.1.7 Proficiency test Schedules shall be developed by each RMAP and 

updated annually for PTs to be organized on a regional level. NIST 

WMD will participate in planning discussions and will evaluate the 

plans for compliance to this policy. NIST WMD will develop and 

update an annual PT plan for programs that require national 

coordination. 

2.1.8 The ILC Plans should be annually reviewed by each region to 

determine if the “frequency” is appropriate. A maximum number of 

PT/ILCs will be coordinated each year based on a balance between the 

full parameters/scopes of the laboratories and a reasonable workload 

due to PTs/ILCs. Coordination among regions is also acceptable to 

allow a new metrologist to participate in an ILC of another region 

without having to wait a number of years for the ILC to be conducted 

in their region. 

2.1.9 This Plan does not preclude additional PT/ILC activities as 

desired/needed. Some examples of special activities include: 

calibration of masses with unique densities or surface finishes, tests of 

density for mass standards, tests of magnetism of mass standards, tests 

of environmental equipment used in buoyancy corrections 

(temperature, pressure, relative humidity), key comparisons, tests for 

new designs of field standards used in weights and measures, tests for 

evaluation of environmental effects on calibration values and 

uncertainties, tests for comparison of procedures, tests for evaluation 

and verification of measurement traceability. 

2.1.10 Tools and forms are available as a part of the NIST/WMD quality 

system for PT/ILC planning and reporting. The tools also include 

laboratory checklists for analysis, corrective action, and laboratory 

follow-up which may help the laboratory document successful PT/ILC 

completion and/or corrective actions where appropriate. 

See example schedule for more information. 
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Sample Proficiency Test Plan 

Metrology 

Area

Branch/Service Level of 

Coordination 

Frequency

At least one “Mass” PT/ILC each year. 

Echelon I NIST or RMAP 2 yr 

Echelon II RMAP 2 yr (Alternated with Echelon I PT) 

Mass

Echelon III RMAP 1 yr: < 10 kg; 

2 yr: 10 kg > x < 200 kg; 

4 yr: > 200 kg 

(Avoirdupois equivalents to metric values will 

be considered based on need and workloads.) 

Volume Echelon I Gravimetric 

Large Volume 

(provers, e.g., 5 gal 

or larger) 

NIST 4 yr 

Small Volume 

(glassware, e.g., < 

1 gal) 

RMAP 4 yr 

Echelon II Volumetric

Large Volume 

Transfer 

NIST or RMAP 2 yr: 5 gal 

5 yr: 15 gal, 100 gal 

Small Volume 

Transfer 

RMAP 4 yr 

Dimensional 

Length Rulers RMAP or NIST 4 yr 

Length Tape 

(Bench or Tape to 

Tape) 

RMAP or NIST 4 yr 

Temperature E.g.: Liquid-In-Glass Thermometers, RTD’s, SPRT’s, Thermistors, Thermocouples 

Echelon 1 NIST 4 yr 

Echelon II NIST 4 yr 

Echelon III NIST 4 yr 

Echelon IV NIST 4 yr 

Echelon V NIST 4 yr 

Hydrometers NIST 4 yr 

Tuning Forks NIST 4 yr 

Time Interval Stop Watches, 

Timing Devices 

NIST 4 yr 

Hygrometers NIST 4 yr 

Grain 

Moisture

NIST or GIPSA 4 yr or more often if required by GIPSA 
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Example Schedule for Each RMAP (or National group) 

NOTE: Some PTs/ILCs will be conducted nationally by NIST/WMD or individuals 

within a region. 

2004 2005 2006 2007 2008 2009 

Mass, 

Echelon I 

Mass, 

Echelon I 

Mass, 

Echelon I 

Mass, 

Echelon II 

Mass, 

Echelon II 

Mass, 

Echelon II 

Mass 

Echelon III 

Mass 

Echelon III 

Mass 

Echelon III 

Mass 

Echelon III 

Mass 

Echelon III 

Mass 

Echelon III 

Volume, 

Echelon I, 

Gravimetric 

Volume, 

Echelon I, 

Gravimetric 

Echelon II, 

Large 

Volume 

Transfer 

(> 5 gal) 

Echelon II, 

Large 

Volume 

Transfer (5 

gal) 

Echelon II, 

Small 

Volume 

Transfer 

(glassware) 

Echelon II, 

Large 

Volume 

Transfer (5 

gal) 

Echelon II, 

Large 

Volume 

Transfer 

(> 5 gal) 

Temperature 

(may also be 

broken down 

by Echelon) 

Dimensional Time Tuning Forks 

Grain 

Moisture 

Hygrometers Hydrometers