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PT Standard Operating Procedure 2 

for

Operating a Mini-Measurement Assurance Program (MiniMAP)

1. Scope or Range of Test

This procedure is for the operation of a small interlaboratory comparison, where there are few 

laboratories (typically between two or three) where a full proficiency test among a regional group 

or a national assessment is not readily available to meet the needs of the laboratory or where there 

is a very small number of laboratories with similar capabilities. Integrated “measurement 

assurance” assessments with additional evaluations of internal control charts and uncertainties to 

supplement the data used for statistical analysis are a key part of conducting small proficiency 

tests, hence the idea for calling them Mini-Measurement Assurance Programs, or “MiniMAPs”. 

Given the limitations in the statistical validity of a small number of participants in a MiniMAP, 

the additional assessments of internal data as specified in this procedure, in addition to the 

proficiency testing (PT) components, are essential. 

This procedure is especially useful for ensuring objective evidence is available to support claims 

of metrological traceability, consistency among laboratories, effective corrective action, evidence 

for adding a new range of calibrations to a laboratory scope of accreditation or scope of 

recognition, or meeting needs where other proficiency tests are not currently or readily available. 

Reasons for conducting such interlaboratory comparisons include comparing measurement results 

among small numbers of laboratories where other PTs are not available, adding something to the 

laboratory scope, completing Laboratory Auditing Program (LAP) problems, validating 

procedures, and for conducting follow-up from a previously failed PTs. See the Reporting section 

for the additional analyses that are part of a complete MiniMAP report. In general, full 

participation in Regional Measurement Assurance Program (RMAP) or National PTs are preferred 

where available.

1.1. PT Process – Required Components

All of the National Institute of Standards and Technology (NIST) Office of Weights and 

Measures (OWM) PT quality management system (QMS) (NISTIR 7082, "Proficiency Test 

Policy Plan" and NISTIR 7214 “Office of Weights and Measures Quality Manual for 

Proficiency Testing and Interlaboratory Comparisons") policies, procedures, and tools must be 

used, including:

PT Plan Template;

Laboratory and staff must be qualified to participate at the planned level of work; 

Review (and approval) of the PT Plan by all participants and by the NIST Office of 

Weights and Measures Laboratory Metrology staff;

Completion of a draft PT Analysis file (using NIST PT software tools) with 

confirmation of data entry by all participants;

Review and approval of the Final PT Report by the NIST Office of Weights and 

Measures Laboratory Metrology staff; 
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Completed PT Follow Up forms for each laboratory; 

Submission of participant calibration certificates for the standards used in the 

MiniMAP (included with the final report); and

Supplemental reporting as noted in Section 6.

1.2. Measurement Parameters, Quantities, and Ranges to be Determined 

This procedure may be used for any measurement parameter and is not limited by measurement 

parameter or range. However, the measurement parameter (the measurand) must be defined 

prior to circulation of the artifact.

1.3. Description of the Item to be Calibrated

Selection of the standards (PT artifacts) require special consideration when they are not part of 

the NIST OWM inventory or when there are a small number of participants. Suitable history, 

stability, resolution, availability of an independent reference value, sufficient accuracy, and 

sufficiently small uncertainties for use with the reference value are critical due to the small 

number of participants in this procedure. The availability of calibrated measurement values for 

the standards used by each laboratory supplements, or reinforces, values selected for the PT 

analysis. 

1.4. Equipment, Including Technical Performance Requirements

All participants must have suitable equipment and reference standards that can provide suitably 

small uncertainties to meet the objectives of the MiniMAP. At least one of the participants 

must have the measurement parameter, range, and uncertainty (Calibration and Measurement 

Capability, CMC) on their Scope of Accreditation. See additional assessments required in the 

Reporting Section.

1.5. Reference Standards and Reference Materials

Suitable independence of reference standard values and working standard values are required. 

I.e., if laboratory B participates in an interlaboratory comparison with laboratory A, where 

laboratory A calibrated the reference standards for laboratory B, there is limited value for the 

two participants. Special care must be taken to avoid comparisons among laboratories that 

could lead to a circular calibration, which would provide traceability to other laboratories over 

the SI. There may be exceptions when selecting participants if a prior calibration was from 

another laboratory and “before and after” calibrations are done based on a calibration of 

reference standards that are being obtained in the process. Artifact and standards history is an 

important part of the MiniMAP process and analysis. If the current certification is circular, 

there may still be adequate history and analysis of data that demonstrates equivalency to an 

adequate level. Thus, increasing the credibility of comparisons.

1.6. Participant Qualifications 

Participating staff must have adequate training prior to the conduct of PTs to ensure that 

standards are not damaged, and that procedures are followed. Qualifications, experience, and 
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training must be documented for each participant (e.g., OWM training transcripts and 

laboratory on-the-job and other training records, and a resume are examples of documented 

requirements. See also Form 2: OWM PT Participation Request – Training/Qualification Form. 

PT policies regarding training and participation must be followed and all participants contact 

information and participating data (even if corrected later) is to be included in the analyses and 

reports. 

2. Procedures, Environmental Conditions, Stabilization Periods, and Handling

Use of internationally or nationally published Standard Operating Procedures (SOPs) is expected 

where available. For compliance with the NIST OWM PT program, NIST SOPs are to be used if 

available. Procedures must be specified or referenced in the PT Plan. If published SOPs are not 

available, all participants must agree to use the same procedures to avoid having discrepancies 

introduced that are procedure dependent. Where method validation is the purpose of the MiniMAP, 

a comparison of the procedures is required as part of the analysis and all procedures must be 

submitted with the report. (This also means that laboratories with proprietary procedures are not 

permitted to participate in a MiniMAP unless they are willing to submit procedures.) A document 

review of non-NIST procedures should be included in the supplementary report. Procedures or 

MiniMAP instructions must include environmental requirements and stabilization periods.

Standards circulated for a MiniMAP may require special handling in addition to the normal 

laboratory administration procedures. If special handling is required, it must be documented in the 

instructions. If the special handling requires training (safety or other) then arrangements should be 

made among all participants. Otherwise, good laboratory practices and administrative procedures 

are followed as for all other calibrations. 

3. PT Analyses (Calculations) (include the Measurement Equations)

The standard OWM approved PT Plan and PT Analysis tools and resources must be used for all 

MiniMAP planning, calculations, and analyses.

4. Measurement Assurance

Laboratory control charts and/or standard deviation charts (where applicable) for the measurement 

process need to be current, have sufficient data, and cover the range and scope of measurements 

being considered. Where suitable control charts or standard deviation charts are not available, 

adequate replications must be performed to assess the repeatability of the measurement process. If 

corrective action is needed with calibration, service, or replacement of equipment, it should be 

done before the MiniMAP is conducted. See Supplemental Reporting Requirements.

5. Uncertainties (include an Uncertainty Budget Table)

If this is a new area on the Scope, additional uncertainty analyses need to be reviewed as a part of 

the laboratory analysis of data prior to issuing the calibration certificate to ensure compliance with 

SOPs and completeness (inclusion of all significant uncertainty components) based on technical 

assessments. See Supplemental Reporting Requirements.

6. Reporting
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A complete “reporting package” is required for all participants for a MiniMAP and is required 

where the results are used for accreditation or recognition purposes, evidence of corrective action, 

demonstration of proficiency, setting or adjusting calibration intervals. Due to the small number 

of participants, there is not adequate data from the PT alone on which to base statistical 

determinations without these additional technical assessments. The following items are required 

to be submitted with the PT Plan (as approved, and with any updates) and PT Analysis files (draft 

and final).

6.1. Calibration certificates. 

Submission of participant calibration certificates for standards used in the calibration is 

required. Traceability hierarchies may be requested.

6.2. Draft PT Analysis file.

Completion of a draft PT analysis report (using NIST PT software tools) with confirmation of 

data entry by all participants is required. Submission of the draft PT Analysis file to OWM is 

required. 

6.3. OWM Review and Approval is Required.

Review and approval of the PT Plan, PT Analysis file(s), and PT Final Report are performed 

by the NIST Office of Weights and Measures.

6.4. A Supplemental Data Analysis Report is Required.

There are many reasons a previous PT might have failed and a number of assessments that 

should be involved supplemental to a final PT report. There are also a number of assessments 

that should be conducted when adding something to a laboratory Scope/CMC. What follows 

is an outline and brief set of questions that are addressed when writing up a supplemental 

assessment to go with a MiniMAP PT Report. There is obvious overlap among the questions, 

so a final supplemental report should be complete and as concise as possible. (e.g., 2 or 3 pages 

would be maximum expected with additional pages of supporting evidence for calibration 

certificates, traceability hierarchies, and control charts, but 6 sentences are too brief). 

Purpose(s) –

• The purpose description may repeat information in the PT Plan and may expand on 

or expound on some of the background issues, concerns, or laboratory goals.

• Demonstration of Traceability. A full traceability assessment is needed to add 

something to a laboratory Scope (see the appendices in GMP 13).

• Demonstration of Competency for Accreditation.

• Demonstration of Effective Corrective Action from Previously Failed PTs.

Reference Standards Assessment

• To verify that values on reference standards or working standards (whichever is 

being considered) continue to be valid requires conducting a calibration history 

assessment of the measurement results over time. Uncertainties due to instability 

may need to be considered and incorporated when needed. As noted earlier, an 
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assessment of the independence of standards used for the MiniMAP must be 

considered. 

• Copies of the traceability hierarchy and relevant calibration certificates need to be 

included. 

Documented Procedures

• Use of NIST published SOPs is expected where available and do not need to be 

submitted with the final package. If NIST SOPs are not available, all participants 

must agree to use the same procedures to avoid having discrepancies introduced 

that are procedure dependent. A document review of non-NIST procedures will be 

conducted by the participants and/or coordinator and included in the supplementary 

report. 

Equipment Assessments

• The measurement process must be assessed and included in the report; data from 

the measurement process is integrated into the uncertainties. Where “bias” from the 

control charts has not previously been included, it must be considered as a part of 

this report. 

• See the “measurement assurance” assessment forms that are available and can be 

used as evidence for the traceability assessment.

• Where the uncertainty budget includes data from the measurement assurance 

systems and lists equipment, the evaluation can be simplified. 

Complete uncertainty analysis

• The updated uncertainties are to be submitted with the PT package and when 

requesting addition to a Scope. Any precision assessment (Pn) failures must include 

corrective action. 

• Special care must be taken with SOP 29, Step 7 for the evaluation of the 

uncertainties to make sure the MiniMAP results are useful for both/all parties. 

Calibration Certificate Assessment

• Given that many of the MiniMAPs are conducted to add something to the Scope, it 

is possible that “template certificates” have not been a part of the laboratory Quality 

Management System and/or need to be updated based on changes and corrective 

actions. All participants should review each other’s certificates in this effort and 

ensure compliance with NISTIR 6969, SOP 1; NIST SP 811; ISO/IEC 17025

Section 7.8 and any other applicable requirements of the calibration parameter, 

including conformity assessments and reference to documentary standards.

PT Follow-up Form

• A PT Follow Up form needs to be completed for each laboratory (not each 

participant) per the earlier notes.