prEN ISO 4259-2

SLOVENSKI STANDARD
01-junij-2025
Nafta in sorodni proizvodi - Natančnost merilnih metod in rezultatov - 2. del:
Razlaga in uporaba podatkov o natančnosti preskusnih metod (ISO/DIS 4259-
2:2025)
Petroleum and related products - Precision of measurement methods and results - Part
2: Interpretation and application of precision data in relation to methods of test (ISO/DIS
4259-2:2025)
Mineralöl und verwandte Produkte - Präzision von Messverfahren und Ergebnissen - Teil
2: Interpretation und Anwendung der Präzisionsdaten von Prüfverfahren (ISO/DIS 4259-
2:2025)
Produits pétroliers et connexes - Fidélité des méthodes de mesure et de leurs résultats -
Partie 2: Interprétation et application des valeurs de fidélité relatives aux méthodes
d'essai (ISO/DIS 4259-2:2025)
Ta slovenski standard je istoveten z: prEN ISO 4259-2
ICS:
75.080 Naftni proizvodi na splošno Petroleum products in
general
75.180.30 Oprema za merjenje Volumetric equipment and
prostornine in merjenje measurements
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

DRAFT
International
Standard
ISO/DIS 4259-2
ISO/TC 28
Petroleum and related products —
Secretariat: NEN
Precision of measurement methods
Voting begins on:
and results —
2025-04-08
Part 2:
Voting terminates on:
2025-07-01
Interpretation and application
of precision data in relation to
methods of test
Produits pétroliers et connexes — Fidélité des méthodes de
mesure et de leurs résultats —
Partie 2: Application des valeurs de fidélité relatives aux
méthodes d'essai
ICS: 75.080
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENTS AND APPROVAL. IT
IS THEREFORE SUBJECT TO CHANGE
AND MAY NOT BE REFERRED TO AS AN
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PUBLISHED AS SUCH.
This document is circulated as received from the committee secretariat.
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Reference number
ISO/DIS 4259-2:2025(en)
DRAFT
ISO/DIS 4259-2:2025(en)
International
Standard
ISO/DIS 4259-2
ISO/TC 28
Petroleum and related products —
Secretariat: NEN
Precision of measurement methods
Voting begins on:
and results —
2025-04-08
Part 2:
Voting terminates on:
2025-07-01
Interpretation and application
of precision data in relation to
methods of test
Produits pétroliers et connexes — Fidélité des méthodes de
mesure et de leurs résultats —
Partie 2: Application des valeurs de fidélité relatives aux
méthodes d'essai
ICS: 75.080
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENTS AND APPROVAL. IT
IS THEREFORE SUBJECT TO CHANGE
AND MAY NOT BE REFERRED TO AS AN
INTERNATIONAL STANDARD UNTIL
PUBLISHED AS SUCH.
This document is circulated as received from the committee secretariat.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
© ISO 2025
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
STANDARDS MAY ON OCCASION HAVE TO
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Published in Switzerland Reference number
ISO/DIS 4259-2:2025(en)
ii
ISO/DIS 4259-2:2025(en)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Application and significance of repeatability, r, and reproducibility, R . 2
4.1 General .2
4.2 Repeatability, r.2
4.2.1 General .2
4.2.2 Acceptability of results .2
4.2.3 Confidence limits calculations using results collected under repeatability
conditions .3
4.3 Reproducibility, R .3
4.3.1 Acceptability of results .3
4.3.2 Confidence limits calculations using results collected under reproducibility
conditions .5
4.4 Use of reproducibility to determine bias between two different test methods that
purport to measure the same property .5
4.4.1 General .5
4.4.2 Process .5
5 Specifications . 6
5.1 Aim of specifications .6
5.2 Construction of specifications limits in relation to scope and precision of the specified
test method .6
6 Assessment of quality conformance to specification . 8
6.1 General .8
6.2 Assessment of quality conformance by the supplier .8
6.3 Assessment of quality conformance by the recipient .9
6.3.1 General .9
6.3.2 Single batch of product .9
6.3.3 Multiple batches of product .9
6.3.4 Procedure for recipient to assess conformance for a single batch of product .10
7 Dispute procedure .11
7.1 Resolve dispute by negotiation .11
7.2 Use of the test method or procedure in case of dispute .11
7.3 Dispute resolution procedure . 12
7.4 Dispute unresolved . 12
7.5 Example of a dispute resolution . 13
Annex A (informative) Explanation of formulae given in Clause 4 .15
Annex B (informative) Dispute resolution for specifications based on a specified degree of
criticality . 17
Annex C (informative) General approach to bias assessment using multiple materials .20
Annex D (informative) Glossary .21
Bibliography .22

iii
ISO/DIS 4259-2:2025(en)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee
has been established has the right to be represented on that committee. International organizations,
governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely
with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 28, Petroleum and related products, fuels and
lubricants from natural or synthetic sources.
This second edition cancels and replaces the first edition (ISO 4259-2:2017), which has been technically
revised.
The main changes are as follows:
— included normative references to ISO 4259-3 and ISO 4259-4;
— deleted annex C because its content is covered by ISO 4259-4;
— improved Figures 2 and 3;
A list of all parts in the ISO 4259 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.

iv
ISO/DIS 4259-2:2025(en)
Introduction
For purposes of setting product specifications, and to check product compliance against these specifications,
standard test methods are usually referenced for specific properties of commercial petroleum and related
products. Two or more measurements of the same property of a specific sample by a specific test method, or
by different test methods that purport to measure the same property, will not usually give exactly the same
result. It is, therefore, necessary to take proper account of this fact when setting product specifications,
assessing if the differences between test results are within statistical expectation, and making specification
compliance decisions based on limited test results. By using statistically-based estimates of the precision
for a test method, the following can be achieved:
— an objective measure of the reliability of specification limits,
— a specification compliance decision, and
— the degree of agreement expected between two or more results obtained in specified circumstances.
This document describes the applications of the precision of test method as derived from ISO 4259-1. It is
intended to be a companion document to ISO 4259-1. Additional normative and informative discussions on
how to use this precision to assess the “in statistical control” status and precision capability of a specific
laboratory in the execution of a test method are provided. Also, the general approach to the agreement
between two different test methods that purport to measure the same property is given.
ISO 4259-1 and ISO 4259-2 encompass both the determination of precision estimates and the application of
[1]
precision data. It attempts to be aligned with ASTM D6300 regarding the determination of the precision
[2]
estimates and with ASTM D3244 for the utilization of test data.
A glossary of the variables used in this document and ISO 4259-1 is included in ISO 4259-1:2024, Annex I.

v
DRAFT International Standard ISO/DIS 4259-2:2025(en)
Petroleum and related products — Precision of measurement
methods and results —
Part 2:
Interpretation and application of precision data in relation to
methods of test
1 Scope
This document specifies the methodology for the application of precision estimates of a test method derived
from ISO 4259-1. In particular, it defines the procedures for setting the property specification limits
based upon test method precision where the property is determined using a specific test method, and in
determining the specification conformance status when there are conflicting results between supplier
and receiver. Other applications of this test method precision are briefly described in principle without the
associated procedures.
The procedures in this document have been designed specifically for petroleum and petroleum-related
products, which are normally homogeneous. However, the procedures described in this document can also
be applied to other types of homogeneous products. Careful investigations are necessary before applying
this document to products for which the assumption of homogeneity can be questioned.
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.
ISO 4259-1, Petroleum and related products — Precision of measurement methods and results — Part 1:
Determination of precision data in relation to methods of test
ISO 4259-3, Petroleum and related products — Precision of measurement methods and results — Part 3:
Monitoring and verification of published precision data in relation to methods of test
ISO 4259-4, Petroleum and related products — Precision of measurement methods and results — Part 4: Use of
statistical control charts to validate 'in-statistical-control' status for the execution of a standard test method in
a single laboratory
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 4259-1 and the following apply.
ISO and IEC maintain terminological 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/

ISO/DIS 4259-2:2025(en)
3.1
proficiency testing scheme
PTS
program designed for the periodic evaluation of participating laboratories’ testing capability of a standard
test method through the statistical analysis of their test results obtained on aliquots prepared from a single
batch of homogeneous material
Note 1 to entry: The frequency of such testing varies in accordance with the program objective. Each execution of
testing involves testing of a single batch of material. Materials typically vary from test to test.
Note 2 to entry: This is also commonly referred to as Inter Laboratory Cross Check Program (ILCP).
3.2
recipient
individual or organization who receives or accepts a product delivered by the supplier (3.3)
3.3
supplier
individual or organization responsible for the quality of a product just before it is taken over by the recipient (3.2)
4 Application and significance of repeatability, r, and reproducibility, R
4.1 General
The value of these quantities is estimated from analysis of variance (two-factor with replication) performed
on the results obtained in a statistically designed inter-laboratory programme in which different
laboratories each test a range of samples. Repeatability and reproducibility values estimated in accordance
with ISO 4259-1 or other statistical techniques shall be included in each published test method.
NOTE See Annex A for an account of the statistical reasoning underlying the formulae Clause 4.
In the following clauses, it is assumed that the result(s) are obtained from a test method that is in statistical
control. For determination of “in statistical control”, see ISO 4259-4.
4.2 Repeatability, r
4.2.1 General
Most laboratories do not carry out more than one test on each sample for routine quality control purposes
except in some circumstances, such as in cases of dispute or if the test operator wishes to confirm that his
technique is satisfactory. In such circumstances, when multiple results are obtained, it is useful to check
the consistency of repeated results against the repeatability of the method. The appropriate procedure is
outlined in 4.2.2. It is also useful to know what degree of confidence can be placed on the average results,
and the method of determining this is given in 4.2.3.
4.2.2 Acceptability of results
When only two results are obtained under repeatability conditions and their difference is less than or equal
to r, the test operator may consider his work as being under control and may take the average of the two
results as the estimated value of the property being tested.
If the two results differ by more than r, both shall be considered as suspect and at least three more results
obtained. Including the first two, the difference between the most divergent result and the average of the
remainder shall then be calculated and this difference compared with a new value, r , instead of r, given in
Formula (1):
ISO/DIS 4259-2:2025(en)
k
rr = (1)
21()k−
where k is the total number of results obtained.
If the difference is less than or equal to r , all the results shall be accepted. If the difference exceeds r ,
1 1
the most divergent result shall be rejected and the procedure specified in this section repeated until an
acceptable set of results is obtained.
The average of the acceptable results shall be taken as the estimated value of the property. However, if
two or more results from a total of not more than 20 have been rejected, the operating procedure and the
apparatus shall be checked and a new series of tests made, if possible.
4.2.3 Confidence limits calculations using results collected under repeatability conditions
When a single test operator, who is working within the precision limits of the method, obtains a series of k
results under repeatability conditions, giving an average, X , and the results meet the repeatability
requirement in 4.2.2, it can be assumed with 95 % confidence that the true value, μ, of the characteristic lies
within the following limits:
 R   R 
X − ≤≤μ X + (2)
   
   
where
 
R =− 1− (3)
Rr
 
k
 
When k = 1, use the single test result as the value for the X term as follows:
 R   R 
X − ≤≤μ X + (4)
   
   
where R is the published test method reproducibility as discussed in 4.3.
Similarly, for the single limit situation, when only one limit is fixed (upper or lower), it can be assumed with
95 % confidence that the true value, μ, of the characteristic is limited as follows:
μ ≤+XR05, 9   (upper limit) (5)
()
or
μ ≥−()XR05, 9   (lower limit) (6)
The factor 0,59 is the ratio 0,84 2 , where 0,84 is derived in Annex A.
When r is much smaller than R, little improvement in the precision of the average is obtained by carrying out
multiple testing under repeatability conditions.
4.3 Reproducibility, R
4.3.1 Acceptability of results
The procedure specified in 4.3 is intended for judging the acceptability, with respect to the reproducibility
of the test method, of results obtained by different laboratories in normal, day-to-day operations and

ISO/DIS 4259-2:2025(en)
transactions. In cases of dispute between a supplier and a recipient, the procedure specified in Clauses 5 to
7 shall be adopted.
When single results are obtained in two laboratories and their difference is less than or equal to R, the two
results shall be considered as acceptable, and used to calculate the average X . The average X , rather than
either single result separately, shall be used as the estimated value of the tested property.
The true value μ of the characteristic is contained within the following limits with a 95 % confidence:
R R
   
X − ≤≤μ X + (7)
   
   
Similarly for the single limit situation, when only one limit is fixed (upper or lower), the true value μ of the
characteristic is contained with the following limits with a 95 % confidence:
μ ≤+()XR04, 2   (upper limit) (8)
or
μ ≥−XR04, 2   (lower limit) (9)
()
The factor 0,42 is the ratio of 05, 92 as it is an average of two results.
If the two results differ by more than R, both shall be considered as suspect. Each laboratory shall then
obtain at least three other acceptable results (see 4.2.2).
In this case, the difference between the averages of all acceptable results of each laboratory shall be judged
for conformity using a new value, R , instead of R, as given by Formula (10):
 1 1 
R =− 1−− (10)
Rr
2  
2kk2
 12
where
R is the reproducibility of the method;
r is the repeatability of the method;
k is the number of results of the first laboratory;
k is the number of results of the second laboratory.
If the difference between the averages is less than or equal to R , then these averages are acceptable and
their overall average shall be considered as the estimated value of the tested property. If the difference
between the averages is greater than R , and there is a dispute on the specification conformance of the
tested property, then the procedure specified in Clause 7 shall be adopted.
If circumstances arise in which there are more than two laboratories, each supplying one or more acceptable
results, the difference between the most divergent laboratory average and the average of the remaining N
laboratory averages shall be compared to R :
where
2 2
R R
1 4
R =+ (11)
22N
ISO/DIS 4259-2:2025(en)
 11 1 
r
R =− N−− −−. (12)
R
4  
N
 kk k 
12 N
R is given in Formula (3), and corresponds to the most divergent laboratory average.
If this difference is equal to or less than R in absolute value, all results shall be regarded as acceptable and
their average taken as the estimated value of the property.
If the difference is greater than R , the most divergent laboratory average shall be rejected and the
comparison using Formulae (11) and (12) repeated until an acceptable set of laboratory averages is obtained.
The average of these laboratory averages shall be taken as the estimated value of the property. However,
if two or more laboratory averages from a total of not more than 20 have been rejected, the operating
procedure and the apparatus shall be checked and a new series of tests made, if possible.
4.3.2 Confidence limits calculations using results collected under reproducibility conditions
When N laboratories obtain one or more results under conditions of repeatability and reproducibility, giving
an average of laboratory averages X , the true value μ of the characteristic is contained within the following
limits with 95 % confidence:
R R
X−≤μ≤+X (13)
22N N
Similarly for the single limit situation, when only one limit is fixed (upper or lower), the true value μ of the
characteristic is contained with the following limits with 95 % confidence:
R
 
μ ≤+X 05, 9   (upper limit) (14)
 
 N 
or
R
 
μ ≥−X 05, 9   (lower limit) (15)
 
 N 
4.4 Use of reproducibility to determine bias between two different test methods that
purport to measure the same property
4.4.1 General
For the situation where two different test methods purport to measure the same property, the reproducibility
estimates (R) from the respective test methods shall be used in conjunction with the averages obtained
from multiple laboratories for the same material to determine if a bias correction can be applied to improve
statistically the agreement between the two methods for that material. For example, results collected
through proficiency testing schemes (PTS) for different test methods using the same sample can be analysed
in this fashion.
NOTE Discussion on methodology for this type of assessment for the simultaneous analysis of multiple materials
/ property levels that span the intersecting scope of two different test methods is beyond the scope of this document.
[3]
Interested readers are encouraged to consult ISO 4259-5 for a detailed presentation on the subject. Annex C provides
a brief overview on the general statistical approach for the aforementioned situation.
4.4.2 Process
Assume that Test Method A and Test Method B are test methods that purport to measure property C.
Calculate the following statistic:

ISO/DIS 4259-2:2025(en)
||YY−
AB
Z= (16)
R R
A B
+
7,,683L 7 683L
A B
where
is the average from L results for property C for a material using Test Method A, where each result
Y
A
A
is a single result obtained under reproducibility conditions;
L is the total number of laboratories (results) for Test Method A and should be >20;
A
R is the reproducibility of Test Method A;
A
is the average from L results for property C for a material using Test Method B on the same material
Y
B
B
tested by Test Method A, where each result is a single result obtained under reproducibility conditions;
L is the total number of laboratories (results) for Test Method B, and should be >20;
B
R is the reproducibility of Test Method B.
B
If Z > 2, it shall be concluded, with 95 % confidence, that a constant bias correction statistically improves the
degree of agreement between Test Method A and Test Method B for property C for this material.
5 Specifications
5.1 Aim of specifications
The purpose of a specification is to specify an acceptable limit or limits to the true value, μ, of the property as
determined by a specified test method. In practice, however, this true value can never be established exactly
since the results obtained by applying the specified test method in a single or multiple laboratories can
show acceptable scattering as defined by the repeatability and reproducibility. There is, therefore, always
some uncertainty as to the true value of the tested property determined from a finite number of test results.
Petroleum product compliance with specifications is assessed in accordance with Clauses 6 and 7. By prior
agreement a supplier and recipient may use the alternative procedures described in Annex B.
It is important that the test method specified for the determination of the property governed by the
specification limit(s) is sufficiently precise to reliably determine whether or not the product meets the
specifications.
5.2 Construction of specifications limits in relation to scope and precision of the specified
test method
The specification limits shall not be outside the method scope limits as determined in ISO 4259-1.
The lower specification limit shall not be less than the lower scope limit of the test method, and the upper
specification limit shall not be greater than the upper scope limit of the test method (see ISO 4259-1:2024; 6.5).
In addition, the distance between lower and upper specification limit shall also satisfy the following
condition: upper specification limit minus lower specification limit shall not be less than the quantity 2R
evaluated at lower method scope limit plus 2R evaluated at upper method scope limit. See Figure 1 for an
illustration of this concept.
ISO/DIS 4259-2:2025(en)
Usually, specifications deal with limits for the values of the properties. To avoid uncertainty, such limits are
normally expressed as “not less than” or “not greater than”. Limits are of two types:
— a double limit, upper and lower, for example viscosity not less than 5 mm /s and not greater than
16 mm /s; boiling point 100 °C ± 0,5 °C;
— a single limit, upper or lower, for example water content not greater than 2 %; sulfur content not greater
than 10 mg/kg ; solubility of bitumen not less than 99 %.
Figure 1 — Specification setting
In cases where, for practical reasons, the value of (A − A ) is less than the above minimum range requirement
1 2
in Figure 1, the results obtained will be of doubtful significance in determining whether a sample does or
does not satisfy the requirements of the specification. According to statistical reasoning, it is desirable for
(A − A ) to be considerably greater than the above minimum range requirement. If not, one or both of the
1 2
following courses shall be adopted:
a) the specification limits shall be examined to see whether they can be widened to fit in with the precision
of the test method;
b) the test method shall be examined to see whether the precision can be improved, or an alternative test
method adopted with an improved precision, to fit in with the desired specification limits.
Conformity to this document requires specifications to be drawn up in accordance with the above principles.

ISO/DIS 4259-2:2025(en)
6 Assessment of quality conformance to specification
6.1 General
6.1.1 Clause 6 provides general information to allow the supplier or the recipient to judge the quality of a
product with regard to the specification based on a single test result as obtained by the supplier or recipient.
If both the supplier's and recipient's single test results are available, the estimate of the true value shall be
obtained in accordance with 4.3. If the recipient decides to dispute the quality conformance to specification
after examining his single result, or the estimate from 4.3, the procedure specified in Clause 7 shall be
adopted.
As a prerequisite for acceptance for laboratory test results to be used in 6.2, 6.3, Clause 7 and Annex B, the
conditions in 6.1.2 to 6.1.4 shall be satisfied.
6.1.2 Each laboratory's test result shall be obtained from a test method that is in statistical control in
terms of precision and bias, as substantiated by in-house SQC charts following the methodologies described
in ISO 4259-4 or other equivalent statistical techniques.
6.1.3 The standard deviation from the control charts (or equivalent statistical techniques) in 6.1.2, as
calculated from at least 30 most recent results obtained over at least 15 days, with results that are separated
by at least 8 h, shall not exceed the published test method standard deviation (R / 2,77).
If evidence exists from the published results of multiple PTS, that the R for a published test method is
statistically inconsistent with the R actually achieved, the latter may be used in lieu of the published R to
judge conformance to this clause, provided all of the following conditions are met:
— if legally permissible, and
— if the R calculated from multiple PTS have sufficient degrees of freedom (>30) using results that have
been properly screened for outliers in accordance with GESD protocol in ISO 4259-1 or other equivalent
statistical technique, and
— upon mutual agreement between disputing parties.
6.1.4 Each laboratory shall be able to demonstrate, by way of results from participation in PTSs, if
available, a sustained testing proficiency and a lack of bias relative to PTS averages assigned in accordance
with ISO 4259-3 Annex B or equivalent statistical techniques for the appropriate test method(s). In the event
that a suitable PTS is not available, proficiency shall be demonstrated by way of testing certified reference
materials (CRM) and in-house control charts on quality control (QC) samples, or by other method validation
techniques acceptable to both parties.
6.2 Assessment of quality conformance by the supplier
A supplier who has no other source of information on the true value of a characteristic than a single result
shall consider, with 95 % confidence, that the product meets the specification limit, only if the result, X , is
s
such that
— in the case of a single upper limit, A :
X ≤ A − 0,59R (17)
s 1
— in the case of a single lower limit, A :
X ≥ A + 0,59R (18)
s 2
— in the case of a double limit (A and A ), both these conditions are satisfied (see 4.2.3).
1 2
ISO/DIS 4259-2:2025(en)
The 95 % confidence decision limits as calculated using Formulae (17) and (18) are for the guidance of the
supplier, and are not to be interpreted as an obligation. A reported value between the specification value and
the limit from Formula (17) or (18) is not proof of non-compliance, but is an indication that the confidence
for the product to meet the specification limit is less than 95 %. If the result is exactly at the specification
limit, the probability of a re-test result meeting specification, by either the supplier or the recipient, is
50 %. A direct consequence of releasing product with a low confidence is that the probability of the receiver
obtaining an off-specification result will be high.
The supplier shall only release the product if their test result meets specification or by mutual agreement
with the customer.
If multiple results are obtained by the supplier under repeatability conditions, the average of the acceptable
results and R as determined in 4.2.2 and 4.2.3 shall be used by the supplier as the basis for determination of
specification conformance.
In the event of a dispute with the recipient, procedures in Clause 7 shall be followed.
6.3 Assessment of quality conformance by the recipient
6.3.1 General
Figure 2 is a procedure flowchart that describes steps outlined in this subclause, taking into account all
available data and requirements of this document.
6.3.2 Single batch of product
A recipient who has no other source of information on the true value of a characteristic than a single result shall
consider that the product fails the specification limit with 95 % confidence, only if the result, x, is such that:
— in the case of an upper limit of the specification A ,
x > A + 0,59R (19)
— in the case of a lower limit of the specification A ,
x < A − 0,59R (20)
— in the case of a double limit (A and A ), either of these conditions applies.
1 2
The 95 % confidence decision limits as calculated using Formulae (19) and (20) is for the guidance of the
recipient, and is not to be interpreted as an obligation. A reported value between the specification value and
the limit from Formula (19) or (20) is not proof of non-conformance, but is an indication that the confidence
for the product failing specification limit is less than 95 %. If the result is exactly at the specification limit,
the probability of a re-test meeting specification, by either the supplier or recipient, is 50 %.
If multiple results are obtained by the recipient under repeatability conditions, the average of the
acceptable results and R as determined in 4.2.3 shall be used as the basis for determination of specification
conformance.
If the recipient decides to dispute the specification conformance status for the batch in question, regardless
of the recipient's result that was used as a basis for the decision to dispute, the procedures in Clause 7 shall
be adhered to.
6.3.3 Multiple batches of product
Persistent results over multiple batches that fail to meet the specification limit, but by an amount not greater
than 0,59R, is a strong indication that the product release confidence by the supplier is less than 95 %. If the

ISO/DIS 4259-2:2025(en)
latter is not acceptable by the recipient, it is recommended that the recipient contact the supplier and arrive
at a mutually satisfactory resolution.
NOTE Five results in a row that fail to meet the specification limit constitute compelling evidence (greater than
95 % confidence) that at least one of the batches does not meet specification.
Figure 2 — Flowchart for assessment of specification conformance by recipient
6.3.4 Procedure for recipient to assess conformance for a single batch of product
In the case of assessing the conformance to specification of a single batch of product, the following example
[5]
shows how to evaluate the process. The Research Octane Number (RON) specification within EN 228
[6]
tested by ISO 5164 is used as an example. The reproducibility of RON using this method is 0,7 RON at the
EN 228 specification of 95,0 RON and the repeatability at the same level is 0,2 RON.
In this example, a supplier sells a batch of gasoline as compliant with EN 228 after certifying the product at
their chosen laboratory as meeting specification. The supplier RON result is 95,1 against the specification of
95,0 and the batch is sold Free On Board (FOB). The sales contract specifies the representative sample as the
shore tank sample which is stored appropriately and in sufficient volume for any follow-up testing.
The recipient purchases the batch and takes a sample to check for quality and the result from their chosen
laboratory is determined as 94,7, which is off-specification but within 0,59R. Subclause 6.3.2 indicates
that the product fails the specification limit with 95 % confidence only if it exceeds the specification by an
amount greater than 0,59R; this is not the case for this example. It is common for the test against 0,59R to be
the end of the procedure unless data from multiple batches is available.
In this case, despite the guidance in 6.3.2, the recipient is unhappy with their result and contacts the supplier
regarding their result. Both are able to confirm and demonstrate that the results came from laboratories
that have in-house SQC programs that are in control with respect to precision and bias for testing using
ISO 5164 and that they regularly par
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