SIST ISO 14807:2011
Photography - Transmission and reflection densitometers - Method for determining performance
Photography - Transmission and reflection densitometers - Method for determining performance
Defines a common set of reporting parameters and describes the methods to be used in the determination and presentation of individual desitometer performance and manufacturer-reported performance specifications. Applies to transmission and reflection densitometers typically manufactured for and used by the photographic, graphic arts and radiographic trades.
Photographie - Densitomètres à transmission et à réflexion - Méthode pour la déterminaiton de la performance
Fotografija - Transmisijski in refleksijski denzitometri - Metoda za določanje zmogljivosti
Opredeljuje splošni set poročevalnih parametrov in opisuje metode, ki se uporabljajo pri določanju in predstavitvi zmogljivosti posameznih denzitometrov in specifikacij zmogljivosti, ki jih navaja proizvajalec. Velja za transmisijske in refleksijske denzitometre, ki so praviloma proizvedeni za uporabo v fotografski stroki, grafični umetnosti in radiografski stroki.
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INTERNATIONAL ISO
STANDARD 14807
First edition
2001-10-15
Photography — Transmission and
reflection densitometers — Method for
determining performance
Photographie — Densitomètres à transmission et à réflexion — Méthode
pour la détermination de la performance
Reference number
ISO 14807:2001(E)
©
ISO 2001
---------------------- Page: 1 ----------------------
ISO 14807:2001(E)
PDF disclaimer
This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but shall not
be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In downloading this
file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat accepts no liability in this
area.
Adobe is a trademark of Adobe Systems Incorporated.
Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation parameters
were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In the unlikely event
that a problem relating to it is found, please inform the Central Secretariat at the address given below.
© ISO 2001
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic
or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISO's member body
in the country of the requester.
ISO copyright office
Case postale 56 � CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.ch
Web www.iso.ch
Printed in Switzerland
ii © ISO 2001 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 14807:2001(E)
Contents Page
Foreword.iv
Introduction.v
1 Scope .1
2 Normative references .1
3 Terms and definitions .1
4 Sampling and handling .5
5 Determination of performance .5
5.1 General.5
5.2 Repeatability determination.5
5.3 Stability determination .6
5.3.1 8 h stability determination .6
5.3.2 7 day stability determination .6
5.4 Bias estimate determination.7
6 Reporting (individual instrument performance).8
6.1 General.8
6.2 Repeatability reporting.8
6.3 Stability reporting .9
6.4 Bias estimate reporting.9
7 Reporting (performance specifications) .10
Bibliography.11
© ISO 2001 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO 14807:2001(E)
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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 3.
Draft International Standards adopted by the technical committees are circulated to the member bodies for voting.
Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this International Standard may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights.
International Standard ISO 14807 was prepared by Technical Committee ISO/TC 42, Photography.
iv © ISO 2001 – All rights reserved
---------------------- Page: 4 ----------------------
ISO 14807:2001(E)
Introduction
Over the past few years, the subject of densitometer performance specifications has been discussed at length, with
the observation made that the densitometer customer is met with a plethora of claims and specifications, in a
variety of formats, pertaining to densitometer performance. Furthermore, various manufacturers have often used
different terminology for describing what is speculated to be the same characteristic. With this in mind, this
International Standard was developed and it identifies three characteristics of performance: ISO repeatability, ISO
stability and ISO bias estimate. Standardized methods for evaluating these characteristics are presented herein.
Any or all three of these characteristics can be evaluated and used to describe the performance of an individual
densitometer and will be useful in comparisons of the performance of densitometers.
The first two of these characteristics, ISO repeatability and ISO stability, are evaluated in such a way that, by use of
suitable periodic sampling of production, a densitometer manufacturer can report average or typical repeatability
and stability as specifications for a particular class, type or model of densitometer. However, ISO bias estimate
cannot necessarily be meaningfully averaged over such a class, type or model, since by determining a mean bias
estimate, any instruments that are biased positively will be offset by any that are biased negatively. Because of this,
bias estimate for a class, type or model of densitometer (if determined as a simple arithmetic mean of the bias
estimates determined for individuals of that class, type or model) is of limited (if any) value and should not be
reported. If determined as such an arithmetic mean, it may only be meaningful if that entire class, type or model is
fraught with a systematic design defect. There is currently no agreement as to the most meaningful way to provide
an ISO bias estimate for a class, type or model of densitometer.
The standardized methods for determination of ISO repeatability and ISO stability provide manufacturers with a
uniform basis for stating densitometer performance characteristics as specifications, thereby providing the
customer with the most useful information.
To clarify and provide mutual understanding, a list of definitions applicable to the performance characteristics has
been provided.
© ISO 2001 – All rights reserved v
---------------------- Page: 5 ----------------------
INTERNATIONAL STANDARD ISO 14807:2001(E)
Photography — Transmission and reflection densitometers —
Method for determining performance
1 Scope
This International Standard defines a common set of reporting parameters and describes the methods to be used in
the determination and presentation of individual densitometer performance and manufacturer-reported performance
specifications. This International Standard applies to transmission and reflection densitometers typically
manufactured for and used by the photographic, graphic arts and radiographic trades.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of
this International Standard. For dated references, subsequent amendments to, or revisions of, any of these
publications do not apply. However, parties to agreements based on this International Standard are encouraged to
investigate the possibility of applying the most recent editions of the normative documents indicated below. For
undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC
maintain registers of currently valid International Standards.
ISO 5-1:1984, Photography — Density measurements — Part 1: Terms, symbols and notations
ISO 5-2:2001, Photography — Density measurements — Part 2: Geometric conditions for transmission density
ISO 5-3:1995, Photography — Density measurements — Part 3: Spectral conditions
ISO 5-4:1995, Photography — Density measurements — Part 4: Geometric conditions for reflection density
ISO 554:1976, Standard atmospheres for conditioning and/or testing — Specifications
3 Terms and definitions
For the purposes of this International Standard, the following terms and definitions apply.
NOTE There are a number of terms that are commonly used in connection with the subject of measurement, such as bias,
repeatability, stability and traceability. One can avoid confusion by using such terms in a way that is consistent with other
international documents. Definitions of many such terms are given in the International Vocabulary of Basic and General Terms
1)
[2]
in Metrology , the title of which is commonly abbreviated, as VIM. The VIM was developed by ISO Technical Advisory
Group4(TAG4).
3.1
true value (of a quantity)
value consistent with the definition of a given particular quantity
NOTE 1 This is a value that would be obtained by a perfect measurement.
1) Throughout this International Standard, raised numbers in square brackets refer to informative documents listed in the
bibliography.
© ISO 2001 – All rights reserved 1
---------------------- Page: 6 ----------------------
ISO 14807:2001(E)
NOTE 2 True values are by nature indeterminate.
NOTE 3 The indefinite article “a”, rather than the definite article “the”, is used in conjunction with “true value” because there
may be many values consistent with the definition of a given particular quantity.
[VIM:1993, 1.19]
3.2
conventional true value (of a quantity)
value attributed to a particular quantity and accepted, sometimes by convention, as having an uncertainty
appropriate for a given purpose
[VIM:1993, 1.20]
NOTE 1 “Conventional true value” is sometimes called assigned value, best estimate of the value, conventional value or
reference value.
NOTE 2 An assigned value of a certified reference material is one type of conventional true value.
3.3
measurand
particular quantity subject to measurement
EXAMPLE Vapour pressure of a given sample of water at 20 °C.
NOTE The specification of a measurand may require statements about quantities such as time, temperature and pressure.
[VIM:1993, 2.6]
3.4
repeatability (of results of measurements)
closeness of the agreement between the results of successive measurements of the same measurand carried out
under the same conditions of measurement
NOTE 1 These conditions are called repeatability conditions.
NOTE 2 Repeatability conditions include:
� the same measurement procedure
� the same observer
� the same measuring instrument, used under the same conditions
� the same location
� repetition over a short period of time.
NOTE 3 Repeatability may be expressed quantitatively in terms of the dispersion characteristics of the results.
[VIM:1993, 3.6]
3.5
experimental standard deviation
s
for a series of n measurements of the same measurand, the quantity s characterizing the dispersion of the results
and given by the formula:
n
2
xx�
��
i
�
i�1
s �
n�1
2 © ISO 2001 – All rights reserved
---------------------- Page: 7 ----------------------
ISO 14807:2001(E)
x being the result of the ith measurement and x being the arithmetic mean of the n results considered
i
[VIM:1993, 3.8]
3.6
systematic error
mean that would result from an infinite number of measurements of the same measurand carried out under
repeatability conditions minus a true value of the measurand
[VIM:1993, 3.14]
NOTE Like true value, systematic error and its causes cannot be completely known.
3.7
stability
ability of a measuring instrument to maintain constant its metrological characteristics with time
NOTE 1 Where stability with respect to a quantity other than time is considered, this should be stated explicitly.
NOTE 2 Stability may be quantified in several ways, for example:
� in terms of the time over which a metrological characteristic changes by a stated amount, or
� in terms of the change in a characteristic over a stated time.
[VIM:1993, 5.14]
3.8
error (of indication) of a measuring instrument
indication of a measuring instrument minus a true value of the corresponding input quantity
[VIM:1993, 5.20]
3.9
bias (of a measuring instrument)
systematic error of the indication of a measuring instrument
NOTE The bias of a measuring instrument is normally estimated by averaging the error of indication over an appropriate
number of repeated measurements.
[VIM:1993, 5.25]
3.10
traceability
property of the result of a measurement or the value of a standard whereby it can be related to stated references,
usually national or international standards, through an unbroken chain of comparisons all having stated
uncertainties
NOTE 1 The concept is often expressed by the adjective traceable.
NOTE 2 The unbroken chain of comparisons is called a traceability chain.
[VIM:1993, 6.10]
EXAMPLE If a ruler used to measure the width of a sheet of paper has been calibrated to a more accurate ruler and this,
in turn, has been calibrated to precision gauge blocks, the measured value of the width of the paper would be traceable to the
gauge blocks (provided the uncertainties of all steps are known).
© ISO 2001 – All rights reserved 3
---------------------- Page: 8 ----------------------
ISO 14807:2001(E)
3.11
calibration
set of operations that establish, under specified conditions, the relationship between values of quantities indicated
by a measuring instrument or measuring system, or values represented by a material measure or a reference
material, and the corresponding values realized by standards
[VIM:1993, 6.11]
3.12
reference material (RM)
material or substance one or more of whose property values are sufficiently homogeneous and well established to
be used for the calibration of an apparatus, the assessment of a measurement method, or for assigning values to
materials
[VIM:1993, 6.13]
3.13
certified reference material (CRM)
reference material, accompanied by a certificate, one or more of whose property values are certified by a
procedure which establishes traceability to an accurate realisation of the unit in which the property values are
expressed, and for which each certified value is accompanied by an uncertainty at a stated level of confidence
[VIM:1993, 6.14]
3.14
combined standard uncertainty
u
c
standard uncertainty of the result of a measurement when that result is obtained from the values of a number of
other quantities, equal to the positive square root of a sum of terms, the terms being the variances or covariances
of these other quantities weighted according to how the measurement result varies with changes in these quantities
[1]
[2.3.4 of the Guide to the Expression of Uncertainty in Measurement:1993 .]
3.15
coverage factor
k
numerical factor used as a multiplier of the combined standard uncertainty in order to obtain an expanded
uncertainty
NOTE 1 A coverage factor, k, is typically in the range 2 to 3.
NOTE 2 The coverage factor is chosen based on the level of confidence desired. A coverage factor (k) of 2 generally will
result in a level of confidence of approximately 95 %, and a coverage factor of 3 generally will result in a level of confidence of
approximately 99 %. This association of confidence level and coverage factor is based on assumptions regarding the probability
distribution of measurement results. For a more thorough explanation, the Guide to the Expression of Uncertainty in
[1]
Measurement:1993 should be consulted.
[This definition and the first note are taken from 2.3.6 of the Guide to the Expression of Uncertainty in
[1]
Measurement:1993 .]
3.16
expanded uncertainty
U
quantity defining an interval about the result of a measurement that may be expected to encompass a large fraction
of the distribution of values that could reasonably be attributed to the measurand
[1]
[2.3.5 of the Guide to the Expression of Uncertainty in Measurement:1993 .]
NOTE Expanded uncertainty is the product of the combined standard uncertainty (u ) and the chosen coverage factor (k).
c
4 © ISO 2001 – All rights reserved
---------------------- Page: 9 ----------------------
ISO 14807:2001(E)
4 Sampling and handling
In determining any of the ISO performance characteristics of an individual densitometer, the densitometer shall be
stored, handled and operated in accordance with the manufacturer’s instructions. Alternatively, a user may wish to
evaluate the performance of a densitometer when operated in conditions or by following methods not
recommended by the manufacturer. In the latter case, though the evaluation may prove useful for a particular
application, the results of such an evaluation shall not be reported as “ISO repeatability”, “ISO stability” or “ISO bias
estimate”. In such a case, any deviation from the manufacturer's instructions should be reported.
In a manufacturer's determination of performance specifications of ISO repeatability and ISO stability, it is important
that the densitometers evaluated yield results that may be expected by users. This will require evaluation of a
statistically valid sampling of dens
...
SLOVENSKI STANDARD
SIST ISO 14807:2011
01-julij-2011
)RWRJUDILMD7UDQVPLVLMVNLLQUHIOHNVLMVNLGHQ]LWRPHWUL0HWRGD]DGRORþDQMH
]PRJOMLYRVWL
Photography - Transmission and reflection densitometers - Method for determining
performance
Photographie - Densitomètres à transmission et à réflexion - Méthode pour la
déterminaiton de la performance
Ta slovenski standard je istoveten z: ISO 14807:2001
ICS:
37.040.10 Fotografska oprema. Photographic equipment.
Projektorji Projectors
SIST ISO 14807:2011 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
---------------------- Page: 1 ----------------------
SIST ISO 14807:2011
---------------------- Page: 2 ----------------------
SIST ISO 14807:2011
INTERNATIONAL ISO
STANDARD 14807
First edition
2001-10-15
Photography — Transmission and
reflection densitometers — Method for
determining performance
Photographie — Densitomètres à transmission et à réflexion — Méthode
pour la détermination de la performance
Reference number
ISO 14807:2001(E)
©
ISO 2001
---------------------- Page: 3 ----------------------
SIST ISO 14807:2011
ISO 14807:2001(E)
PDF disclaimer
This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but shall not
be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In downloading this
file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat accepts no liability in this
area.
Adobe is a trademark of Adobe Systems Incorporated.
Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation parameters
were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In the unlikely event
that a problem relating to it is found, please inform the Central Secretariat at the address given below.
© ISO 2001
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic
or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISO's member body
in the country of the requester.
ISO copyright office
Case postale 56 � CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.ch
Web www.iso.ch
Printed in Switzerland
ii © ISO 2001 – All rights reserved
---------------------- Page: 4 ----------------------
SIST ISO 14807:2011
ISO 14807:2001(E)
Contents Page
Foreword.iv
Introduction.v
1 Scope .1
2 Normative references .1
3 Terms and definitions .1
4 Sampling and handling .5
5 Determination of performance .5
5.1 General.5
5.2 Repeatability determination.5
5.3 Stability determination .6
5.3.1 8 h stability determination .6
5.3.2 7 day stability determination .6
5.4 Bias estimate determination.7
6 Reporting (individual instrument performance).8
6.1 General.8
6.2 Repeatability reporting.8
6.3 Stability reporting .9
6.4 Bias estimate reporting.9
7 Reporting (performance specifications) .10
Bibliography.11
© ISO 2001 – All rights reserved iii
---------------------- Page: 5 ----------------------
SIST ISO 14807:2011
ISO 14807:2001(E)
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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 3.
Draft International Standards adopted by the technical committees are circulated to the member bodies for voting.
Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this International Standard may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights.
International Standard ISO 14807 was prepared by Technical Committee ISO/TC 42, Photography.
iv © ISO 2001 – All rights reserved
---------------------- Page: 6 ----------------------
SIST ISO 14807:2011
ISO 14807:2001(E)
Introduction
Over the past few years, the subject of densitometer performance specifications has been discussed at length, with
the observation made that the densitometer customer is met with a plethora of claims and specifications, in a
variety of formats, pertaining to densitometer performance. Furthermore, various manufacturers have often used
different terminology for describing what is speculated to be the same characteristic. With this in mind, this
International Standard was developed and it identifies three characteristics of performance: ISO repeatability, ISO
stability and ISO bias estimate. Standardized methods for evaluating these characteristics are presented herein.
Any or all three of these characteristics can be evaluated and used to describe the performance of an individual
densitometer and will be useful in comparisons of the performance of densitometers.
The first two of these characteristics, ISO repeatability and ISO stability, are evaluated in such a way that, by use of
suitable periodic sampling of production, a densitometer manufacturer can report average or typical repeatability
and stability as specifications for a particular class, type or model of densitometer. However, ISO bias estimate
cannot necessarily be meaningfully averaged over such a class, type or model, since by determining a mean bias
estimate, any instruments that are biased positively will be offset by any that are biased negatively. Because of this,
bias estimate for a class, type or model of densitometer (if determined as a simple arithmetic mean of the bias
estimates determined for individuals of that class, type or model) is of limited (if any) value and should not be
reported. If determined as such an arithmetic mean, it may only be meaningful if that entire class, type or model is
fraught with a systematic design defect. There is currently no agreement as to the most meaningful way to provide
an ISO bias estimate for a class, type or model of densitometer.
The standardized methods for determination of ISO repeatability and ISO stability provide manufacturers with a
uniform basis for stating densitometer performance characteristics as specifications, thereby providing the
customer with the most useful information.
To clarify and provide mutual understanding, a list of definitions applicable to the performance characteristics has
been provided.
© ISO 2001 – All rights reserved v
---------------------- Page: 7 ----------------------
SIST ISO 14807:2011
---------------------- Page: 8 ----------------------
SIST ISO 14807:2011
INTERNATIONAL STANDARD ISO 14807:2001(E)
Photography — Transmission and reflection densitometers —
Method for determining performance
1 Scope
This International Standard defines a common set of reporting parameters and describes the methods to be used in
the determination and presentation of individual densitometer performance and manufacturer-reported performance
specifications. This International Standard applies to transmission and reflection densitometers typically
manufactured for and used by the photographic, graphic arts and radiographic trades.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of
this International Standard. For dated references, subsequent amendments to, or revisions of, any of these
publications do not apply. However, parties to agreements based on this International Standard are encouraged to
investigate the possibility of applying the most recent editions of the normative documents indicated below. For
undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC
maintain registers of currently valid International Standards.
ISO 5-1:1984, Photography — Density measurements — Part 1: Terms, symbols and notations
ISO 5-2:2001, Photography — Density measurements — Part 2: Geometric conditions for transmission density
ISO 5-3:1995, Photography — Density measurements — Part 3: Spectral conditions
ISO 5-4:1995, Photography — Density measurements — Part 4: Geometric conditions for reflection density
ISO 554:1976, Standard atmospheres for conditioning and/or testing — Specifications
3 Terms and definitions
For the purposes of this International Standard, the following terms and definitions apply.
NOTE There are a number of terms that are commonly used in connection with the subject of measurement, such as bias,
repeatability, stability and traceability. One can avoid confusion by using such terms in a way that is consistent with other
international documents. Definitions of many such terms are given in the International Vocabulary of Basic and General Terms
1)
[2]
in Metrology , the title of which is commonly abbreviated, as VIM. The VIM was developed by ISO Technical Advisory
Group4(TAG4).
3.1
true value (of a quantity)
value consistent with the definition of a given particular quantity
NOTE 1 This is a value that would be obtained by a perfect measurement.
1) Throughout this International Standard, raised numbers in square brackets refer to informative documents listed in the
bibliography.
© ISO 2001 – All rights reserved 1
---------------------- Page: 9 ----------------------
SIST ISO 14807:2011
ISO 14807:2001(E)
NOTE 2 True values are by nature indeterminate.
NOTE 3 The indefinite article “a”, rather than the definite article “the”, is used in conjunction with “true value” because there
may be many values consistent with the definition of a given particular quantity.
[VIM:1993, 1.19]
3.2
conventional true value (of a quantity)
value attributed to a particular quantity and accepted, sometimes by convention, as having an uncertainty
appropriate for a given purpose
[VIM:1993, 1.20]
NOTE 1 “Conventional true value” is sometimes called assigned value, best estimate of the value, conventional value or
reference value.
NOTE 2 An assigned value of a certified reference material is one type of conventional true value.
3.3
measurand
particular quantity subject to measurement
EXAMPLE Vapour pressure of a given sample of water at 20 °C.
NOTE The specification of a measurand may require statements about quantities such as time, temperature and pressure.
[VIM:1993, 2.6]
3.4
repeatability (of results of measurements)
closeness of the agreement between the results of successive measurements of the same measurand carried out
under the same conditions of measurement
NOTE 1 These conditions are called repeatability conditions.
NOTE 2 Repeatability conditions include:
� the same measurement procedure
� the same observer
� the same measuring instrument, used under the same conditions
� the same location
� repetition over a short period of time.
NOTE 3 Repeatability may be expressed quantitatively in terms of the dispersion characteristics of the results.
[VIM:1993, 3.6]
3.5
experimental standard deviation
s
for a series of n measurements of the same measurand, the quantity s characterizing the dispersion of the results
and given by the formula:
n
2
xx�
��
i
�
i�1
s �
n�1
2 © ISO 2001 – All rights reserved
---------------------- Page: 10 ----------------------
SIST ISO 14807:2011
ISO 14807:2001(E)
x being the result of the ith measurement and x being the arithmetic mean of the n results considered
i
[VIM:1993, 3.8]
3.6
systematic error
mean that would result from an infinite number of measurements of the same measurand carried out under
repeatability conditions minus a true value of the measurand
[VIM:1993, 3.14]
NOTE Like true value, systematic error and its causes cannot be completely known.
3.7
stability
ability of a measuring instrument to maintain constant its metrological characteristics with time
NOTE 1 Where stability with respect to a quantity other than time is considered, this should be stated explicitly.
NOTE 2 Stability may be quantified in several ways, for example:
� in terms of the time over which a metrological characteristic changes by a stated amount, or
� in terms of the change in a characteristic over a stated time.
[VIM:1993, 5.14]
3.8
error (of indication) of a measuring instrument
indication of a measuring instrument minus a true value of the corresponding input quantity
[VIM:1993, 5.20]
3.9
bias (of a measuring instrument)
systematic error of the indication of a measuring instrument
NOTE The bias of a measuring instrument is normally estimated by averaging the error of indication over an appropriate
number of repeated measurements.
[VIM:1993, 5.25]
3.10
traceability
property of the result of a measurement or the value of a standard whereby it can be related to stated references,
usually national or international standards, through an unbroken chain of comparisons all having stated
uncertainties
NOTE 1 The concept is often expressed by the adjective traceable.
NOTE 2 The unbroken chain of comparisons is called a traceability chain.
[VIM:1993, 6.10]
EXAMPLE If a ruler used to measure the width of a sheet of paper has been calibrated to a more accurate ruler and this,
in turn, has been calibrated to precision gauge blocks, the measured value of the width of the paper would be traceable to the
gauge blocks (provided the uncertainties of all steps are known).
© ISO 2001 – All rights reserved 3
---------------------- Page: 11 ----------------------
SIST ISO 14807:2011
ISO 14807:2001(E)
3.11
calibration
set of operations that establish, under specified conditions, the relationship between values of quantities indicated
by a measuring instrument or measuring system, or values represented by a material measure or a reference
material, and the corresponding values realized by standards
[VIM:1993, 6.11]
3.12
reference material (RM)
material or substance one or more of whose property values are sufficiently homogeneous and well established to
be used for the calibration of an apparatus, the assessment of a measurement method, or for assigning values to
materials
[VIM:1993, 6.13]
3.13
certified reference material (CRM)
reference material, accompanied by a certificate, one or more of whose property values are certified by a
procedure which establishes traceability to an accurate realisation of the unit in which the property values are
expressed, and for which each certified value is accompanied by an uncertainty at a stated level of confidence
[VIM:1993, 6.14]
3.14
combined standard uncertainty
u
c
standard uncertainty of the result of a measurement when that result is obtained from the values of a number of
other quantities, equal to the positive square root of a sum of terms, the terms being the variances or covariances
of these other quantities weighted according to how the measurement result varies with changes in these quantities
[1]
[2.3.4 of the Guide to the Expression of Uncertainty in Measurement:1993 .]
3.15
coverage factor
k
numerical factor used as a multiplier of the combined standard uncertainty in order to obtain an expanded
uncertainty
NOTE 1 A coverage factor, k, is typically in the range 2 to 3.
NOTE 2 The coverage factor is chosen based on the level of confidence desired. A coverage factor (k) of 2 generally will
result in a level of confidence of approximately 95 %, and a coverage factor of 3 generally will result in a level of confidence of
approximately 99 %. This association of confidence level and coverage factor is based on assumptions regarding the probability
distribution of measurement results. For a more thorough explanation, the Guide to the Expression of Uncertainty in
[1]
Measurement:1993 should be consulted.
[This definition and the first note are taken from 2.3.6 of the Guide to the Expression of Uncertainty in
[1]
Measurement:1993 .]
3.16
expanded uncertainty
U
quantity defining an interval about the result of a measurement that may be expected to encompass a large fraction
of the distribution of values that could reasonably be attributed to the measurand
[1]
[2.3.5 of the Guide to the Expression of Uncertainty in Measurement:1993 .]
NOTE Expanded uncertainty is the product of the combined standard uncertainty (u ) and the chosen coverage factor (k).
c
4 © ISO 2001 – All rights reserved
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SIST ISO 14807:2011
ISO 14807:2001(E)
4 Sampling and handling
In determining any of the ISO performance characteristics of an individual densitometer, the densitometer shall be
stored, handled and operated in accordance with the manufacturer’s instructions. Alternatively, a user may wish to
evaluate the performance of a densitometer when operated in conditions or by following methods not
recommended by the manufacturer. In the latter case, though t
...
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