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GLP 14

Good Laboratory Practice

for 

Procedure for Method Validation

1 Introduction

This is the metrology laboratory policy and procedure for developing and validating test or 

calibration methods when no international or national procedures are available, when deviating 

from standardized methods, or when no standard procedures are available.

2 Purpose

The Metrology Laboratory follows this procedure to ensure that all laboratory methods selected, 

modified, or developed for tests and calibrations are appropriate for the intended use, properly 

documented, validated, accepted by laboratory management, and agreed upon by the client. 

Customers of the Laboratory expect a given service to provide acceptable measurement results 

when they request a test or calibration. The laboratory must evaluate each method to ensure that it 

has qualified and competent staff, suitable facilities, equipment, and standards with acceptable 

metrological traceability to perform the test or calibration. 

3 Responsibility 

The Laboratory Supervisor or Quality Manager ensures the following, in 

consultation with the laboratory staff as needed: 

development of methods is a planned activity and assigned to qualified staff 

with appropriate resources;

for larger projects, plans are updated as progress is made and effectively 

communicated to all personnel; and

ensures the certificate for the test or calibration is compliant with standard 

requirements and customer needs.

The Technical Manager reviews the documented procedure, data, and analysis, and 

recommends final acceptance to the Laboratory Manager or Quality Manager based 

on the suitability of the procedure and acceptability of observed analysis of 

measurement results.

The Laboratory Supervisor or Quality Manager is responsible for final acceptance 

of new calibration methods, training staff on the new procedure, and for consistent 

implementation. 
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4 Operations

If the laboratory does not have an appropriate method for a calibration or test, or 

the test or calibration requires deviation to meet the needs of the customer, the 

Technical Manager is notified and this procedure is implemented.

When determining whether to proceed in developing new test or calibration method 

to meet the needs of a customer, the Laboratory Supervisor or Quality Manager and 

Technical Manager consider at least the following factors:

availability of alternative procedures (national or international standards);

resources of the laboratory and staffing (time, efficiency); and

likely future demand for the service. 

The staff conducting the Contract Review for the calibration or test must obtain a 

clear specification of the customer requirements and the purpose of the test or 

calibration including any tolerances or maximum uncertainties that are required for 

the item/sample end usage (to ensure that the measurement results will be fit for 

purpose).

New methods must be developed prior to performing the tests or calibrations and 

contain the following information:

Appropriate identification (title); 

Scope or range of test; 

Description of the type of item to be tested or calibrated; 

Parameters or quantities and ranges to be determined; 

Apparatus and equipment, including technical performance requirements; 

Reference standards and reference materials required; 

Environmental conditions required, and any stabilization period needed; 

Description of the procedure, including any special items as noted in this 

list: 

4.4.8.1 Affixing of identification marks, handling, transporting, storing and 

preparation of items, 

4.4.8.2 Checks to be made before the work is started, 

4.4.8.3 Checks that the equipment is working properly and, where required, 

calibration and adjustment of the equipment before each use, 
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4.4.8.4 Method of recording the observations, data to be recorded, data 

reduction, method of analysis, and presentation of results, and 

4.4.8.5 Safety measures to be observed; 

Criteria and/or requirements for approval/rejection where applicable; 

Data to be recorded and method of analysis and presentation; and 

Uncertainty or the procedure for estimating uncertainty. 

5 Method Validation

Non-standardized methods, which include all laboratory developed methods, 

standardized methods modified beyond their intended scope and amplifications and 

modifications of standardized methods, are validated by:

Examination to ensure completeness and compliance with requirements for 

essential components of metrological traceability; and 

Analysis of objective evidence to ensure the requirements for a specific 

intended purpose are fulfilled prior to use.

Validation methods are to be as extensive as necessary to meet the needs of their 

intended application. Adequate measurement data is obtained to ensure statistical 

validity of the evaluated results. The accuracy and uncertainty of test or calibration 

results shall be assessed for the intended use, and shall be relevant to the client’s 

needs.

Validation procedures and results are recorded, with a statement concerning the 

appropriateness of the new method as it pertains to the intended use.

Validation techniques include one or a combination of the following:

Calibration/verification and evaluation of bias and precision using 

calibrated working standards;

Comparison of results achieved with other standardized methods;

Method evaluation through variations of controlled parameters (e.g., one 

variable at a time) to determine robustness; 

Inter-laboratory comparisons when practical;

Systematic assessment of factors influencing the results; and 

Evaluation of the uncertainty of results based on scientific understanding of 

the theoretical principles associated with the method and practical 

experience.
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When changes are made in the validated non-standardized procedures, the influence 

of such changes must be documented and, if appropriate, a new validation process 

carried out. 

The following types of assessments, with data and statistical analysis are examples 

that may be used to assess the measurement results (See Appendix A form):

Inspection and technical assessment of the essential elements of 

metrological traceability to ensure presence and adequacy (technical review 

may include representatives from other laboratories, working groups, 

technical experts, and assessors):

5.6.1.1 Reference to the international system of units (SI);

5.6.1.2 Unbroken chain of calibrations to national and/or international 

standards;

5.6.1.3 Suitable and up to date calibration intervals for standards used in the 

procedure;

5.6.1.4 Documented procedure (reviewed to ensure completeness against 

the list of items in Section 4.d.);

5.6.1.5 Documented measurement uncertainty (as noted in Section 4.d.v.);

5.6.1.6 Demonstrated technical competence;

5.6.1.7 Adequate measurement assurance approach and supporting data.

Accuracy or Limits to Bias may use data obtained from internal testing 

and/or interlaboratory comparisons: t-test, normalized error (En), absolute 

or relative bias versus required tolerance limits;

Precision: standard deviation, normalized precision (Pn), F-test, comparison 

to required uncertainties (fit for purpose and meeting needs of the customer)

Repeatability: assessment of results over time and by different operators 

following the procedure as documented; and 

Reproducibility: assessment of data from other laboratories following the 

procedure.

6 Records. (See Appendix A for summary of validation records to be supplemented with 

appropriate data, analysis, and evaluation records.) 

Laboratory records shall be retained for all aspects of the procedure validation for 

as long as the procedure remains in valid use, including but not limited to:

Validation procedure (and version) that is used;
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Any applicable specifications and/or tolerances; 

Evaluation of performance characteristics and summaries; 

Observed data and measurement results; 

Approval for use by the customer; and

A statement that the method is valid and suitable for its intended use. 

7 Implementation

A laboratory developed test or calibration method is validated, reviewed by the 

Technical Manager, reviewed by the Quality Manager, and approved by the 

Laboratory Supervisor.

The method is documented and formatted into a written Standard Operating 

Procedure (SOP) document and assigned an identification number. The new SOP 

will be added to the laboratory Master List.

Staff are trained and competency is confirmed. 

All laboratory method validation documentation is kept on file in the laboratory 

and maintained according to the Quality Management System.

8 Acknowledgment and Validation

This publication was presented as part of a collection of draft Standard Administrative Procedures 

in 1996 and has been adopted by many weights and measures laboratories in some form since that 

time. The procedure has also been used in NIST seminars covering calibration procedure 

validation as a part of compliance with ISO/IEC 17025. 
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Appendix A

Evaluation Form for Method Validation Review

Procedure Evaluated: ____________________________________

Evaluation Conducted by: ____________________________________

Method Evaluation Observations

Procedure is complete and contains:

 appropriate identification (title); 

 scope or range of test; 

 description of the type of item to be tested or calibrated; 

 parameters or quantities and ranges to be determined; 

 apparatus and equipment, including technical performance 

requirements; 

 reference standards and reference materials required; 

 environmental conditions required and any stabilization 

period needed; 

 description of the procedure, including any special items as 

noted in this list: 

 affixing of identification marks, handling, transporting, 

storing and preparation of items, 

 checks to be made before the work is started, 

 checks that the equipment is working properly and, 

where required, calibration and adjustment of the 

equipment before each use, 

 the method of recording the observations, data to be 

recorded, data reduction, method of analysis, and 

presentation of results, and 

 any safety measures to be observed; 

 criteria and/or requirements for approval/rejection where 

applicable; 

 data to be recorded and method of analysis and 

presentation; and 

 the uncertainty or the procedure for estimating uncertainty.

Essential Elements of Traceability are Defined (5.f, i) See GMP 

13.

Realization of SI Units. The primary national, international, or 

intrinsic standards must be primary standards for the realization 

of the International System of Units (SI);

Unbroken chain of comparisons. A documented system of 

comparisons with each step having the essential elements of 

metrological traceability going back to a standard acceptable to 

the parties, usually a national or international standard; Are 

suitable standards identified in the procedure?
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Method Evaluation Observations

Standard Calibrations & Intervals. Calibrations of standards 

(and equipment where appropriate) must be repeated at 

established (may be defined through measurement assurance) 

and appropriate intervals to preserve metrological traceability of 

the standard over time and use (see GLP 4, GMP 11); Are 

suitable calibration intervals defined for the standards used in 

this procedure?

Documented Measurement Uncertainty. The measurement 

uncertainty for each step in the traceability chain must be 

calculated according to defined methods and must be stated so 

that an overall uncertainty for the whole chain may be 

calculated (see SOP 29); Is the uncertainty budget completely 

defined based on a comparison of similar procedures or 

technical reference documents (describe the procedures and/or 

references)

Documented Measurement Procedure. Each step in the chain 

must be performed according to documented and generally 

acknowledged procedures (see GMP 12) and the results must be 

documented (i.e., in a calibration certificate, see SOP 1); Is the 

procedure complete according to all required elements? 

(4.d)

Accredited Technical Competence. The laboratories or bodies 

performing one or more steps in the chain must supply evidence 

of technical competence (e.g., by maintaining appropriate 

training records, participating in interlaboratory comparisons, 

and by demonstrating that they are accredited by a recognized 

accreditation body); Have all staff been trained and have they 

demonstrated competency with the procedure? Have any other 

laboratories provided input or tried to duplicate the procedure? 

Was an interlaboratory comparison or proficiency test 

conducted? Describe the results.

Measurement assurance. A proper measurement assurance 

program must be established to ensure the validity of the 

measurement process and the accuracy of standard used at the 

time of the measurement (see SOPs 9, 17, 20, 30). What type of 

measurement assurance is integrated into the procedure? 

Describe what the measurement assurance monitors (standards, 

process, both? How?)

Additional Assessments

Comparison of Results with Other Procedures. Describe what 

other procedures or standards were considered and why/why 

not chosen? Describe the results obtained and analysis 

conducted with multiple procedures. 

Evaluation of Accuracy and Bias. (5.f.ii)

What are the limits to bias or error? How do you know the 

results are right? Describe the recently calibrated standard/set 

of standards that were used. Describe any standard reference 

materials that were used. How were the results assessed for 

Accuracy?
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Method Evaluation Observations

Evaluation of Precision. How was data for repeatability 

obtained? Describe whether the precision assessment is shortterm or long-term and if short-term, how do you know how the 

procedure will repeat over time? How do you know whether the 

precision is sufficiently small when incorporated into 

uncertainties? Describe the statistical assessments that were 

completed and document the analysis results.

Evaluation of Repeatability. E.g., two different units were 

evaluated after a recent (enter dates) calibration by multiple 

metrologists; what kind of statistics were used and what were 

the results? (Consider repeatability with different staff, 

equipment, standards/nominal values, and not just short-term 

precision.)

Evaluation of Reproducibility. Have any other laboratories 

provided input or tried to duplicate the procedure? Was an 

interlaboratory comparison or proficiency test conducted? 

Describe the results.

3rd Party Assessment or Technical Reviews. Have any other 

technical experts reviewed the procedure and provided input? 

Describe their assessment and any recommended improvements 

or changes that were implemented because of the review. 

This procedure has found to be complete, fit for its intended use, technically validated, meets customer needs, 

and is approved for use.

Quality Manager Signature Technical Manager Signature

Quality Manager Name (Printed) Technical Manager Name (Printed)

Date Date
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Appendix B

Example Outline for a Standard Operating Procedure 

(Title)

1 Scope and Measurand(s) of Calibrations 

2 Description of the Item to be Calibrated

3 Measurement Parameters, Quantities, and Ranges to be Determined 

4 Equipment, Including Technical Performance Requirements 

5 Reference Standards and Reference Materials

6 Environmental Conditions and Stabilization Periods 

7 Procedure Include any special items as noted in this list: 

Affixing of identification marks, handling, transporting, storing and preparation 

of items; 

Checks to be made before the work is started; 

Checks that the equipment is working properly and, where required, calibration 

and adjustment of the equipment before each use; 

Step by step process: the method of recording the observations, data to be 

recorded, data reduction, method of analysis, and presentation of results; 

Any safety measures to be observed; 

Criteria and/or requirements for approval/rejection where applicable; 

Data to be recorded and method of analysis and presentation; 

8 Calculations (See Possible Measurement Equations) 

9 Measurement Assurance (possible Check Standards)

10 Uncertainties (include an Uncertainty Budget Table)

11 Calibration Certificate
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