FprCEN/TS 18405

• Abstract:

  This document provides guidance to harmonize the expression of metrological information such as measurement uncertainties and decision rules in standards for furniture.; This document clarifies how to deal with measurement uncertainty of measurement results, and how to express information concerning measurement uncertainty in furniture standards.

• Status: Not Published
• Publication Date: 20-Jan-2027
• ICS: 17.020 - Metrology and measurement in general
• ICS: 97.140 - Furniture
• Technical Committee: CEN/TC 207 - Furniture
• Drafting Committee: CEN/TC 207/WG 9 - Test methods
• Current Stage: 5020 - Submission to Vote - Formal Approval
• Start Date: 03-Sep-2026
• Due Date: 13-Oct-2025
• Completion Date: 03-Sep-2026
• Ref Project: kSIST-TS FprCEN/TS 18405:2026 - Furniture - General guidelines about measurement uncertainty

FprCEN/TS 18405 is a CEN draft Technical Specification for furniture. It gives general guidance on how to express measurement uncertainty and decision rules in furniture standards, so test results can be reported and judged in a consistent way. It is written for standards writers, testing laboratories, and others who need to interpret furniture measurements in practice.

What does FprCEN/TS 18405 specify?

FprCEN/TS 18405 specifies guidance for harmonizing metrological information in furniture standards, especially measurement uncertainty and decision rules. In practice, it tells standards developers and test labs how to describe a measured value together with its uncertainty, and how to decide whether a result meets a requirement.

The document is organized into six clauses and two informative annexes.

Part	What it covers
Clause 1	Scope
Clause 2	Normative references
Clause 3	Terms and definitions
Clause 4	Measurement uncertainty
Clause 5	Decision rule
Clause 6	Tolerances
Annex A	Worked examples of measurement uncertainty evaluation
Annex B	Interlaboratory comparisons and collaborative trials

Annex A separates three common result types: continuous numerical results, discrete numerical results, and pass/fail results. Annex B focuses on collaborative trials and how interlaboratory comparison data can support uncertainty assessment.

What are the key requirements of FprCEN/TS 18405?

Measurement uncertainty must be considered

FprCEN/TS 18405 says that whenever a furniture standard refers to a quantity to be measured, measurement uncertainty shall be considered. The document points to typical uncertainty sources such as sampling, the measurement method, equipment, environmental conditions, the operator, the time between repeated measurements, and the place of measurement. For a reader, this means uncertainty is not an optional add-on - it is part of the measurement result that affects conformity decisions.

The document also distinguishes repeatability conditions and reproducibility conditions. Repeatability uses the same procedure, operator, system, location and short time interval, while reproducibility allows more variation between laboratories or conditions. In practice, repeatability uncertainty is expected to be smaller, so it is useful for checking how well one laboratory performs.

Standards should state uncertainty information clearly

Clause 4 recommends that a standard include target measurement uncertainty, any available interlaboratory comparison results, the documents used to calculate uncertainty, and any neglected contributions. It also notes that some environmental effects may be negligible if conditions stay within specified limits, and that sampling uncertainty can be impractical to quantify in mechanical furniture testing. For users, this means the test method should say what matters, what can be ignored, and what target the laboratory is expected to meet.

The clause also allows repeated-measurement information to be expressed using repeatability limit r and reproducibility limit R. That matters when a test method reports precision data instead of a full uncertainty budget.

Decision rules are required for conformity claims

Clause 5 says that when a standard has an acceptance limit or range, it should state how to judge compliance of a measurement result that includes uncertainty. FprCEN/TS 18405 gives two example approaches: one that compares the measured value directly with the limit, and another that compares the measured value adjusted by expanded uncertainty U. The practical point is that a laboratory should know whether uncertainty is ignored or included when declaring compliance.

The clause also says different requirements in the same standard may use different decision rules. When a statement of conformity is issued, the laboratory shall document the decision rule used and the risk associated with it, in line with EN ISO/IEC 17025:2017.

Tolerances need a decision rule too

Clause 6 extends the same idea to tolerances on physical quantities such as mass, force, and time. It says the standard shall state how the measured value, the nominal value, and the expanded uncertainty are checked against the tolerance range. In practice, this lets users decide whether a test input or measured quantity stays within the allowed interval.

What terms does FprCEN/TS 18405 define?

• quantity - a property that can be expressed by a number and a reference.
• measurement uncertainty - a non-negative parameter describing the dispersion of values attributed to a measurand.
• measurement result - the set of values attributed to a measurand together with relevant information, usually a value plus uncertainty.
• expanded measurement uncertainty (U) - a combined standard uncertainty multiplied by a factor greater than 1.
• target measurement uncertainty - an upper limit for uncertainty chosen for the intended use of the results.
• repeatability condition of measurement - same procedure, operator, system, conditions, and location over a short time.
• reproducibility condition of measurement - measurements made with variation in locations, operators, or systems.
• decision rule - the rule used to decide whether a result complies with a requirement.

Who uses FprCEN/TS 18405?

FprCEN/TS 18405 is used by furniture standards developers, testing laboratories, conformity assessment bodies, and quality or metrology staff working with furniture test methods. It is especially relevant where standards involve dimensions, forces, masses, angles, velocities, or time.

In practice, users apply it when writing test methods, estimating uncertainty, comparing interlaboratory data, and documenting how compliance is judged. It is also useful for labs that need to show that their own uncertainty or repeatability matches the target stated in a furniture standard.

Which standards are used with FprCEN/TS 18405?

• EN ISO/IEC 17025:2017 - the main normative reference for laboratory competence and for documenting decision rules in conformity statements.
• ISO/IEC 17025 - the international basis of EN ISO/IEC 17025:2017.
• ISO 5725 series - used for the relationship between repeatability/reproducibility limits and uncertainty.
• JCGM 100:2008 - cited for general guidance on evaluating measurement uncertainty.
• JCGM 200:2012 - supplies the vocabulary used for core metrology terms.
• JCGM 106:2012 - provides background on measurement uncertainty in conformity assessment.
• ISO 13528 and EN ISO/IEC 17043 - referenced for interlaboratory comparison and proficiency testing schemes.
• EN 1335-1, ISO 24496, EN 1730, EN 12720, EN 12722, and CEN/TR 17292 - cited in examples and bibliography as furniture test methods and precision-data references.

What does the FprCEN/TS 18405 document contain?

FprCEN/TS 18405 contains general guidance text, not a test method of its own. Clause 4 explains where measurement uncertainty comes from and how to describe it in a furniture standard. Clause 5 gives decision-rule examples and shows acceptance zones with figures, while Clause 6 applies the same logic to tolerances.

Annex A gives worked examples for three result types: a continuous numerical result, a discrete numerical result, and a pass/fail result. Annex B explains how interlaboratory comparisons and collaborative trials support uncertainty assessment and precision data.

SLOVENSKI STANDARD
01-oktober-2026
Pohištvo - Splošne smernice o merilni negotovosti
Furniture - General guidelines about measurement uncertainty
Möbel - Allgemeiner Leitfaden zur Messunsicherheit
Ta slovenski standard je istoveten z: FprCEN/TS 18405
ICS:
17.020 Meroslovje in merjenje na Metrology and measurement
splošno in general
97.140 Pohištvo Furniture
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

FINAL DRAFT
TECHNICAL SPECIFICATION
SPÉCIFICATION TECHNIQUE
TECHNISCHE SPEZIFIKATION
September 2026
ICS 17.020; 97.140
English Version
Furniture - General guidelines about measurement
uncertainty
Möbel - Allgemeiner Leitfaden zur Messunsicherheit

This draft Technical Specification is submitted to CEN members for Vote. It has been drawn up by the Technical Committee
CEN/TC 207.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are
aware and to provide supporting documentation.

Warning : This document is not a Technical Specification. It is distributed for review and comments. It is subject to change
without notice and shall not be referred to as a Technical Specification.

EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2026 CEN All rights of exploitation in any form and by any means reserved Ref. No. FprCEN/TS 18405:2026 E
worldwide for CEN national Members.

Contents Page
European foreword . 3
Introduction . 4
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 5
4 Measurement uncertainty . 7
4.1 General. 7
4.2 Repeatability and reproducibility . 7
4.3 Measurement uncertainty information . 8
5 Decision rule . 8
5.1 General. 8
5.2 First example of decision rule . 8
5.3 Second example of decision rule . 9
5.4 Decision rules in case of many requirements. 10
6 Tolerances . 10
Annex A (informative) Example of measurement uncertainty evaluation . 11
A.1 General. 11
A.2 Test result is a numerical value on a continuous scale . 11
A.3 Test result is a numerical value on a discrete scale . 12
A.4 Test result is a pass/fail value . 12
Annex B (informative) Interlaboratory comparisons (collaborative trials) . 14
B.1 General. 14
B.2 Assessment of compliance of measurement uncertainty of test lab . 14
Bibliography . 15

European foreword
This document (FprCEN/TS 18405:2026) has been prepared by Technical Committee CEN/TC 207
“Furniture”, the secretariat of which is held by UNI.
This document is currently submitted to the Vote on TS.

Introduction
Standards drafted by CEN/TC 207 often involve physical quantities (e.g. forces, masses, dimensions,
angles, velocities, time) and measurement results (composed of a value and its measurement
uncertainty) associated with these quantities.

1 Scope
This document provides guidance to harmonize the expression of metrological information such as
measurement uncertainties and decision rules in standards for furniture.
This document clarifies how to deal with measurement uncertainty of measurement results, and how to
express information concerning measurement uncertainty in furniture standards.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
EN ISO/IEC 17025:2017, General requirements for the competence of testing and calibration laboratories
(ISO/IEC 17025:2017)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https://www.iso.org/obp/
— IEC Electropedia: available at https://www.electropedia.org/
3.1
quantity
property of a phenomenon, body, or substance, where the property has a magnitude that can be
expressed as a number and a reference
[SOURCE: JCGM 200:2012, definition 1.1]
3.2
measurement uncertainty
non negative parameter characterizing the dispersion of the quantity values being attributed to a
measurand, based on the information used
Note 1 to entry: The parameter may be, for example, a standard deviation called standard measurement
uncertainty (or a specific multiple of it), or the half-width of an interval, having a stated coverage probability.
[SOURCE: JCGM 200:2012, definition 2.26]
3.3
measurement result
set of quantity values being attributed to a measurand together with any other available relevant
information
Note 1 to entry: A measurement result is generally expressed as a single measured value and a measurement
uncertainty
[SOURCE: JCGM 200:2012, definition 2.9]
3.4
expanded measurement uncertainty “U”
product of a combined standard measurement uncertainty and a factor larger than the number one
Note 1 to entry: In case of a standard distribution, using a coverage factor k = 2, the probability covered by the
interval “value ± U” is approximately equal to 95 %.
[SOURCE: JCGM 200:2012, definition 2.35]
3.5
target measurement uncertainty
measurement uncertainty specified as an upper limit and decided on the basis of the intended use of
measurement results
[SOURCE: JCGM 200:2012, definition 2.34]
3.6
repeatability condition of a measurement
condition of measurement out of a set of conditions that includes the same measurement procedure,
same operators, same measuring system, same operating conditions and same location, and replicate
measurements on the same or similar objects over a short period of time
[SOURCE: JCGM 200:2012, definition 2.20]
3.7
reproducibility condition of measurement
condition of measurement, out of a set of conditions that includes same locations, operators, measuring
systems, and replicate measurements on the same or similar objects over a short period of time
[SOURCE: JCGM 200:2012, definition 2.24]
3.8
repeatability limit “r”
value less than or equal to which the absolute difference between two test results obtained under
repeatability conditions may be expected to be with a probability of 95 %
[SOURCE: ISO 5725-1:2023, definition 3.17, modified]
3.9
reproducibility limit “R”
value less than or equal to which the absolute difference between two test results obtained under
reproducibility conditions may be expected to be with a probability of 95 %
[SOURCE: ISO 5725-1:2023, definition 3.22, modified]
3.10
decision rule
value less than or equal to which the absolute difference between two test results obtained under
reproducibility conditions may be expected to be with a probability of 95 %
[SOURCE: EN ISO/IEC 17025:2017, definition 3.7]
4 Measurement uncertainty
4.1 General
Whenever a standard refers to a quantity (3.1) to be measured, measurement uncertainty shall be
considered. The sources of measurement uncertainty are generally, but not exhaustingly:
— sampling;
— measurement method;
— equipment used;
— environmental conditions;
— operator;
— time between repeated measurements;
— place where the measurement takes place.
A portion of the measurement uncertainty may arise from repeated measurements and is therefore
influenced by the conditions under which those measurements are performed.
4.2 Repeatability and reproducibility
A distinction is made between repeatability condition of measurement and reproducibility condition of
measurement:
— repeatability condition (3.6);
EXAMPLE of repeatability condition:
One single sample measured by same operator in a single laboratory using the same measuring procedure and
same measuring system.
NOTE 1 An uncertainty derived from measurements taken under repeatability conditions, when specified in a
test method, can be used for performance evaluation. That is, an individual laboratory can assess its performance
by comparing its own measurement uncertainty with the value stated in the test method.
— reproducibility condition (3.7);
EXAMPLE of reproducibility condition:
One single sample measured by different operators in different laboratories using same measuring procedure but
different measuring systems
NOTE 2 An uncertainty derived from measurements taken under reproducibility conditions, when specified in
a test method, provides insight into the maximum expected spread of results across different laboratories or
conditions.
Measurements taken under repeatability conditions are expected to result in a smaller measurement
uncertainty compared to measurements taken under reproducibility conditions, since fewer influencing
factors vary.
4.3 Measurement uncertainty information
A standard can give information about measurement uncertainty. It is recommended that the following
information is include
...