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JJF 1059.1-2012

JJF

METEOROLOGICAL INDUSTRY STANDARD

OF THE PEOPLE’S REPUBLIC OF CHINA

Evaluation and expression of uncertainty in

measurement

[Including Amendment 2013XG1]

ISSUED ON: DECEMBER 03, 2012

IMPLEMENTED ON: JUNE 03, 2013

Issued by: General Administration of Quality Supervision, Inspection and

Quarantine

Table of Contents

Introduction ... 7

1 Scope ... 10

2 Normative references ... 11

3 Terms and definitions ... 12

3.1 Measured [JJF 1001,4.7]... 12

3.2 Measurement results, result of measurement [JJF 1001,5.1] ... 13

3.3 Measured quantity value [JJF 1001,5.2] ... 13

3.4 Measurement precision [JJF 1001, 5.10] ... 14

3.5 Measurement repeatability [JJF 1001, 5.13] ... 14

3.6 Measurement repeatability condition of measurement [JJF 1001, 5.14] ... 14

3.7 Measurement reproducibility [JJF 1001, 5.16] ... 15

3.8 Measurement reproducibility condition of measurement [JJF 1001, 5.15] ... 15

3.9 Intermediate precision condition of measurement [JJF 1001, 5.11] ... 15

3.10 Experimental standard deviation [JJF 1001, 5.17] ... 16

3.11 Measurement error, error of measurement [JJF 1001, 5.3] ... 17

3.12 Measurement uncertainty, uncertainty of measurement [JJF 1001, 5.18] ... 17

3.13 Standard uncertainty [JJF 1001, 5.19] ... 18

3.14 Type A evaluation of measurement uncertainty [JJF 1001, 5.20] ... 18

3.15 Type B evaluation of measurement uncertainty [JJF 1001, 5.21] ... 18

3.16 Combined standard uncertainty [JJF 1001, 5.22] ... 19

3.17 Relative standard uncertainty [JJF 1001, 5.23] ... 19

3.18 Expanded Uncertainty [JJF 1001, 5.27] ... 19

3.19 Coverage interval [JJF 1001, 5.28] ... 20

3.20 Coverage probability [JJF 1001, 5.29]... 20

3.21 Coverage factor [JJF 1001, 5.30] ... 20

3.22 Measurement model, model of measurement [JJF 1001, 5.31] ... 21

3.23 Measurement function [JJF 1001, 5.32] ... 21

3.24 Input quantity in in a measurement model [JJF 1001, 5.33] ... 21

3.25 Output quantity in the measurement model [JJF 1001, 5.34] ... 22

3.26 Definitional uncertainty [JJF 1001, 5.24] ... 22

3.27 Instrumental measurement uncertainty [JJF 1001, 7.24] ... 22

3.28 Null measurement uncertainty [JJF 1001, 7.25] ... 23

3.29 Uncertainty budget [JJF 1001, 5.25] ... 23

3.30 Target uncertainty [JJF 1001, 5.26] ... 23

3.31 Degrees of freedom... 23

3.32 Covariance ... 24

3.33 Correlation coefficient ... 25

4 Evaluation method of measurement uncertainty ... 25

4.1 Analysis of sources of measurement uncertainty ... 26

4.2 Establishment of measurement model ... 27

4.3 Evaluation of standard uncertainty ... 30

4.4 Calculation of combined standard uncertainty ... 42

4.5 Determination of extended uncertainty ... 50

5 Report and expression of measurement uncertainty ... 51

5.1 Report of measurement uncertainty ... 51

5.2 Expression of measurement uncertainty ... 53

5.3 Other requirements when reporting uncertainty ... 55

6 Application of measurement uncertainty ... 56

6.1 Requirements for reporting measurement uncertainty in calibration certificate

... 56

6.2 Laboratory calibration and expression of measurement capability ... 57

6.3 Application in other situations ... 58

Appendix A Examples of evaluation methods of measurement uncertainty

(reference) ... 59

Appendix B Table of tp(ν) values (t values) for t distributions with different

probabilities p and degrees of freedom ν (supplementary) ... 92

Appendix C Summary of symbols related to quantities (supplementary) ... 94

Appendix D English-Chinese contrast of terms (reference) ... 97

Amendment No.1 to JJF 1059.1-2012 "Evaluation and expression of

uncertainty in measurement" ... 99

Evaluation and expression of uncertainty in

measurement

1 Scope

a) The general method for evaluating and expressing measurement

uncertainty specified in this specification is applicable to measurement

fields of various accuracy levels, such as:

1) The establishment of national measurement standards and

measurement standards at all levels and the comparison of values;

2) The setting value of standard substance and the release of standard

reference data;

3) Preparation of technical documents such as measurement methods,

verification procedures, verification system tables, calibration

specifications, etc.;

4) Expression of measurement results and measurement capabilities in

measurement qualification recognition, measurement confirmation,

quality certification, laboratory accreditation;

5) Calibration, verification and other measurement services of measuring

instruments;

6) Measurement in the fields of scientific research, engineering, trade

settlement, medical and health care, safety protection, environmental

monitoring, resource protection.

b) This specification mainly concerns the measurement uncertainty of the

measured estimated value that is clearly defined and can be characterized

by a unique value. As for the measured quantity value that appears as a

distribution of a series of values or depends on one or more parameters

(for example, with time as the parameter variable), the description of the

measured quantity value shall be a set of values, the distribution and

relationship shall be given.

c) This specification is also applicable to the evaluation and expression of

uncertainties in the design and theoretical analysis of experiments,

measuring methods, measuring devices, complex components and

systems.

3 Terms and definitions

The metrology terminology in this specification adopts JJF 1001-2011, which is

based on the revision of international standard ISO/IEC GUIDE 99:2007 (the

third edition of VIM). The probability and statistical terms used in this

specification basically adopt the terms and definitions of the international

standard ISO 3534-1:2006.

3.1 Measured [JJF 1001,4.7]

The amount to be measured.

Note:

1 The description of the measured requires an understanding of the type of

quantity and the description of the phenomena containing the quantity,

objects or substance status, including relevant components and chemical

entities.

2 In the second edition of VIM and IEC 60050-300:2001, the measured is

defined as the measured quantity.

3 The measurement includes the measurement system and the conditions

under which the measurement is carried out. It may change the

phenomenon, object substance in the study, so that the measured quantity

may be different from the defined measured. In this case, it needs

necessary corrections to be made.

Example:

1 When measuring with a voltmeter with insufficient internal resistance, the

potential difference between the two ends of the battery will decrease; the

open circuit potential difference can be calculated based on the internal

resistance of the battery and the voltmeter.

2 The length of the steel bar when it is in equilibrium with the ambient

temperature of 23 °C is different from the length when the specified

temperature to be measured is 20 °C. In this case, it must be corrected.

3 In chemistry, the name of “analyte” or substance or compound is

sometimes called “measured”. This usage is wrong because these terms

do not involve quantity.

measurement is not too small compared with the measurement

uncertainty, the measured quantity value is usually an average or median

estimate of a set of true values.

4 In the Guide to Measurement Uncertainty (GUM), the terms used for the

measured quantity values are "measurement results" and "estimated

measured quantity value" or "estimated measured quantity value".

3.4 Measurement precision [JJF 1001, 5.10]

Referred to as precision

Under the specified conditions, the degree of agreement between the

measured indication value and the measured quantity value through

repeated measurement of the same or similar measured object.

Note:

1 Measurement precision is usually expressed in numerical form with

imprecision, such as standard deviation, variance or coefficient of variation

under specified measurement conditions.

2 The prescribed conditions may be repetitive measurement conditions,

intermediate precision measurement conditions or reproducible

measurement conditions.

3 Measurement precision is used to define measurement repeatability,

intermediate measurement precision or measurement repeatability.

4 The term "measurement precision" is sometimes used to refer to

"measurement accuracy", which is wrong.

3.5 Measurement repeatability [JJF 1001, 5.13]

Referred to as repeatability.

Measurement precision under a set of repeatable measurement conditions.

3.6 Measurement repeatability condition of measurement [JJF

1001, 5.14]

Referred to as repeatability condition.

A set of measurement conditions of repeated measurement on the same or

3.11 Measurement error, error of measurement [JJF 1001, 5.3]

Abbreviated as error.

The measured quantity value minus the reference value.

Note:

1 The concept of measurement error can be used in the following two

situations:

① When it involves the existence of a single reference value, such as

calibration with a measurement standard whose measurement

uncertainty of the measured quantity value is negligible, or when a

quantitative value is given, the measurement error is known;

② Assuming that the measured is characterized by a unique set of true

values or a set of true values with negligible range, the measurement

error is unknown.

2 Measurement errors shall not be confused with errors or faults.

3.12 Measurement uncertainty, uncertainty of measurement

[JJF 1001, 5.18]

Abbreviated as uncertainty

According to the information used, characterize the non-negative

parameters that give the measured quantity value dispersion.

Note:

1 Measurement uncertainty includes components caused by the influence of

the system, such as the component related to the correction value and the

assigned value of the measurement standard as well as the definitional

uncertainty. Sometimes the estimated system impact is not corrected, but

treated as an uncertainty component.

2 This parameter can be such as the standard deviation (or a specific

multiple of it) called the standard measurement uncertainty, or it can

specify the half width of the interval containing the probability.

3 The measurement uncertainty generally consists of several components.

Some of these components can be evaluated according to the statistical

different from the type A evaluation of measurement uncertainty.

Example: The evaluation is based on the following information:

- The value issued by the authority;

- The value of certified reference materials;

- Calibration certificate;

- Instrument drift;

- Accuracy level of certified measuring instruments;

- Inferred limit values based on personnel experience.

3.16 Combined standard uncertainty [JJF 1001, 5.22]

Full name is combined standard measurement uncertainty.

The standard measurement uncertainty of the output quantity obtained from

the standard measurement uncertainty of each input quantity in a

measurement model.

Note: In the case where the input in the measurement model is relevant, the

covariance must be considered when calculating the combined standard

uncertainty.

3.17 Relative standard uncertainty [JJF 1001, 5.23]

Full name is relative standard measurement uncertainty

The absolute value that is obtained by dividing the standard uncertainty by

the measured quantity value.

3.18 Expanded Uncertainty [JJF 1001, 5.27]

Full name is expanded measurement uncertainty.

The product of the combined standard uncertainty and a digital factor greater

than 1.

Note:

1 This factor depends on the type of probability distribution of the output in

3.22 Measurement model, model of measurement [JJF 1001,

5.31]

Referred to as model.

The mathematical relationship between all known quantities involved in the

measurement.

Note:

1 The general form of the measurement model is the formula: h(Y, X1,..., XN)

= 0, where the output Y in the measurement model is measured, whose

value is derived from the relevant information of the input quantity X1, ...,

XN in the measurement model.

2 In more complex situations with two or more outputs, the measurement

model contains more than one formula.

3.23 Measurement function [JJF 1001, 5.32]

In the measurement model, when the value calculated from the known

quantity of the input quantity is the measured quantity value of the output

quantity, the functional relationship between the input quantity and the output

quantity.

Note:

1 If the measurement model h (Y, X1, ..., XN) = 0 can be explicitly written as

Y = f(X1, ..., XN), where Y is the output in the measurement model, then

the function f is the measurement function. In more layman's terms, f is an

algorithm symbol, which is used to calculate the only output quantity y =

f(x1, ..., xN) corresponding to the input quantity x1, ..., xN.

2 The measurement function is also used to calculate the measurement

uncertainty of the measured quantity value Y.

3.24 Input quantity in in a measurement model [JJF 1001, 5.33]

Referred to as input quantity.

The quantity that must be measured in order to calculate the measured

quantity value being measured, or its value can be obtained in other ways.

B measurement uncertainty.

3 Information about the measurement uncertainty of the instrument can be

given in the instrument manual.

3.28 Null measurement uncertainty [JJF 1001, 7.25]

The measurement uncertainty when the measured quantity value is zero.

Note:

1 The null measurement uncertainty is related to the indication of zero or

close to zero. It contains the interval of the measurement being too small

to know whether it can be detected, or the indication interval of the

measuring instrument is caused only by noise.

2 The concept of null measurement uncertainty also applies when measuring

the difference between the sample and the blank.

3.29 Uncertainty budget [JJF 1001, 5.25]

Statement of measurement uncertainty, including the components of

measurement uncertainty and their calculation and synthesis.

Note: The uncertainty report shall include the measurement model, the

estimated value, the measurement uncertainty associated with each quantity

in the measurement model, the covariance, the type of probability density

distribution function used, the degrees of freedom, the evaluation type of the

measurement uncertainty, the coverage factors.

3.30 Target uncertainty [JJF 1001, 5.26]

Full name is target measurement uncertainty.

According to the intended use of the measurement results, the measurement

uncertainty which is specified as the upper limit.

3.31 Degrees of freedom

In the calculation of variance, the number of sums minus the limit of sums.

Note:

1 Under repeatability conditions, when n independent measurements are

uncertainty of the instrument;

g) The inaccuracy of the standard value provided by the measurement

standard or reference material;

h) Inaccurate values of quoted constants or other parameters;

i) Approximations and assumptions in measurement methods and

measurement procedures;

j) Under the same conditions, the changes of measured repeated

observations.

The source of measurement uncertainty must be specifically analyzed

according to the actual measurement situation. In the analysis, in addition to

the definitional uncertainty, it can be comprehensively considered from the

aspects of measuring instruments, measuring environment, measuring

personnel, measuring methods. In particular, pay attention to the sources of

uncertainty that have a greater impact on the measurement results; try to avoid

missing or repetition.

4.1.3 The correction is only to compensate the system error; the correction

value is uncertain. When evaluating the measurement uncertainty of the

corrected measured estimated value, it shall consider the uncertainty

introduced by the correction. Only when the uncertainty of the correction value

is small and the contribution to the combined standard uncertainty is negligible,

it may not be considered.

4.1.4 Errors or sudden factors in the measurement are not a source of

measurement uncertainty. In the evaluation of measurement uncertainty, the

outliers in the measured quantity values shall be eliminated. The elimination of

outliers shall be carried out after proper inspection of the data.

Note: The judgment and processing method of outliers can be found in GB/T

4883-2008 "Statistical interpretation of data - Detection and treatment of outliers

in the normal sample".

4.2 Establishment of measurement model

4.2.1 In the measurement, when the measured (i.e. output quantity) Y is

determined by N other quantities X1, X2, ..., XN (i.e. input quantity) through the

function f, the formula (1) is called the measurement model:

Where the capital letters represent the symbol of quantity, f is the measurement

is helpful to establish the measurement model when using the verification

standard and control chart method to indicate that the measurement process is

always in the state of statistical control.

4.2.5 If the data indicates that the measurement function fails to model the

measurement process to the accuracy required for measurement, additional

input must be added to the measurement model to reflect the lack of knowledge

of the amount of influence.

4.2.6 The input quantity in the measurement model can be:

a) The quantity directly measured by the current. These quantities and their

uncertainties can be obtained by single observation, repeated observation

or empirical estimation; it can include correction values for readings of

measuring instruments and correction values for influence quantities such

as ambient temperature, atmospheric pressure, humidity, etc.

b) Quantity introduced by external sources. Such as the quantity of calibrated

measurement standards or certified reference materials, as well as the

reference data found in the manual.

4.2.7 When analyzing measurement uncertainty, the uncertainty of each input

quantity in the measurement model is the source of the uncertainty of the output

quantity.

4.2.8 This specification is mainly applicable when the measurement model is a

linear function. If it is a non-linear function, Taylor series expansion shall be

adopted and its high-order terms shall be ignored; the measured quantity value

shall be approximated as a linear function of the input value, so as to evaluate

the measurement uncertainty. If the measurement function is obviously non-

linear, the evaluation of the combined standard uncertainty must include the

main higher-order terms in the Taylor series expansion.

4.2.9 When the best estimated value y of the measured Y is obtained through

the estimated value x1, x2, ..., xN of the input quantities X1, X2, ..., XN, there are

two calculation methods: formula (5) and formula (6):

a) Calculation method I:

Where, y is the arithmetic average of the measured quantity values yk

obtained by n independent measurements of Y; the uncertainty of each

measured quantity value yk is the same; each yk is obtained by a complete

set of measured quantity value based on the N input quantities Xi as

obtained at the same time.

This method can increase the degree of freedom of the standard uncertainty of

the evaluation, thus improve the credibility.

4.3.2.6 Pre-evaluation of repeatability

In the routine verification, calibration or detection work of the same type of the

test piece, if the measurement system is stable and there is no obvious change

in the measurement repeatability, the measurement system can be used, using

the same procedure, operator, at the same location with the test piece under

measurement, to make n pre-measurements on the typical measured quantity

value of the typical test piece (generally n is not less than 10), to calculate the

experimental standard deviation s(xk) of the single measured quantity value

from the Bessel formula, that is, the measurement repeatability. When actually

measuring a certain test piece, it can only measure n’ times (1 ≤ n’ < n), take

the arithmetic average value of n’ independent measurements as the estimated

value of the measured, then the type A standard uncertainty of this measured

estimate value due to repeatability is calculated according to formula (20):

The degree of freedom of standard uncertainty as evaluated by this method is

still ν = n - 1. It shall be noted that when the repeatability of the measurement

is suspected to be changed, the experimental standard deviation s(xk) shall be

re-measured and calculated in time.

4.3.2.7 When the estimated value xi of the input quantity Xi is obtained from the

curve fitted by the experimental data by the method of least squares, any point

on the curve and the standard uncertainty characterizing the curve fitting

parameters can be evaluated by the relevant statistical procedures. If the

measured estimated value xi presents a time-dependent random change in

multiple observations, a special statistical analysis method shall be used. For

example, in frequency measurement, the Allen standard deviation (Allen

variance) is used.

4.3.2.8 Type A evaluation methods are usually more objective than those

obtained by other evaluation methods, meanwhile are statistically rigorous, but

require a sufficient number of repetitions. In addition, the measured quantity

values as obtained by repeated measurements in this measurement procedure

shall be independent of each other.

4.3.2.9 The source of random effects shall be considered as much as possible

in the type A evaluation, so that it can be reflected in the measured quantity

value.

Note: For example:

u(xi) and u(xj) - The standard uncertainty of xi and xj.

4.4.4.3 Use appropriate methods to remove correlations

a) Introduce the correlation-induced quantity into the measurement model as

an independent additional input quantity

For example, if the measurement model of the measured estimated value

is y = f(xi, xj), when determining the measured Y, use a thermometer to

determine the temperature correction value xi of the estimated value of

the input Xi, meanwhile use the same thermometer to determine the

temperature correction value xj of the estimated value of the other input

quantity Xj, the two temperature correction values xi and xj are obviously

correlated. xi = F(T), xj = G(T), that is, both xi and xj are related to the

temperature; because the same thermometer is used for measurement,

if the thermometer shows a large value, the correction values of both are

affected at the same time, so the two input quantities xi and xj in y = f[xi(T),

xj(T)] are correlated. However, as long as the temperature T is used as

an independent additional input in the measurement model, that is, y =

f(xi, xj, T), wherein xi, xj are the estimated values of the input quantities Xi,

Xj, the input quantity T has the standard uncertainty which is not related

to the above two quantities, so there is no need to introduce the

covariance or correlation coefficient of xi and xj when calculating the

combined standard uncertainty.

b) Take effective measures to transform the input quantity

For example, the uncertainty component of the calibration value in the

calibration of the gauge block includes two input quantities: the

temperature θs of the standard gauge block and the temperature θ of the

calibrated gauge block, that is, L = f(θs, θ, ...). Since the two gauge blocks

are on the same measuring device in the laboratory, the temperatures θs

and θ are related. But as long as θ is transformed into θ = θs + δθ, the

temperature difference δθ of the calibrated block and the standard block

and the temperature θs of the standard block are used as two input

quantities, at this time the two input quantities are not related, that is, the

θs in L = f(θs, δθ, ...) is not related to δθ.

4.4.5 Effective degrees of freedom of combined standard uncertainty

4.4.5.1 The degree of freedom of the combined standard uncertainty uc(y) is

called the effective degree of freedom, which is represented by the symbol νeff.

It indicates the reliability of the evaluated uc(y). The greater the νeff, the more

reliable the evaluated uc(y).

4.4.5.2 Effective degrees of freedom νeff need to be calculated in the following

shall be as detailed as possible, so that users can correctly use the

measurement results. Only for certain uses, if the measurement uncertainty is

considered to be negligible, the measurement result can be expressed as a

single measured quantity value, without reporting its measurement uncertainty.

5.1.2 Generally, when reporting the following measurement results, the

combined standard uncertainty uc(y) is used; if necessary, its effective degree

of freedom νeff is given:

a) Basic metrology research;

b) Measurement of basic physical constants;

c) International comparison reproducing the units of international units

(according to relevant international provisions, it may also use the

extended uncertainty of k = 2).

5.1.3 In addition to the above provisions or the parties concerned agreed to the

use of combined standard uncertainty, usually when reporting measurement

results, they are expressed as extended uncertainty.

When it comes to the measurement of industry, commerce, health and safety,

if there are no special requirements, the extended uncertainty U will be reported,

which is generally taken as k = 2.

5.1.4 The measurement uncertainty report generally includes the following:

a) The measurement model being measured;

b) Sources of uncertainty;

c) The value of the standard uncertainty u(xi) of the input quantity as well as

its evaluation method and evaluation process;

d) Sensitivity coefficient ;

e) Uncertainty component of output quantity ui(y) = ci u(xi), if necessary, give

the degrees of freedom of each component νi;

f) Give the covariance or correlation coefficient for all relevant input quantities;

g) The combined standard uncertainty uc and its calculation process, if

necessary, give the effective degree of freedom νeff;

h) Extended uncertainty U or Up and its determination method;

i) Report the measurement results, including the estimated value being

U or Up, including the unit of measurement;

c) If necessary, it may also give the relative expanded uncertainty Urel;

d) It shall give the value of k for U; give p and νeff for Up.

5.2.2.1 U = kuc(y) report can be in one of the following four forms.

For example, the mass of the standard weight is ms, the estimated value being

measured is 100.02147 g, uc(y) = 0.35 mg, the coverage factor k = 2, U = 2 ×

0.35 mg = 0.70 mg, then it is reported as follows:

a) ms = 100.02147 g, U = 0.70 mg; k = 2.

b) ms = (100.02147 ± 0.00070) g; k = 2.

c) ms = 100.02147 (70) g; for the U value of k = 2 in parentheses, the last

digit is aligned with the last digit in the previous result.

d) ms = 100.02147 (0.00070) g; the U value when k = 2 in parentheses has

the same measurement unit as the previous result.

5.2.2.2 Up = kpuc(y) can be reported in one of the following four forms.

For example, the mass of the standard weight is ms, the estimated value

measured is 100.02147 g, uc(y) = 0.35 mg, νeff = 9, according to p = 95%, check

Appendix B to get kp = t95(9) = 2.26, U95 = 2.26 × 0.35 mg = 0.79 mg, then:

a) ms = 100.02147 g, U95 = 0.79 mg, νeff = 9.

b) ms = (100.02147 ± 0.00079) g, νeff = 9, the second item in brackets is the

value of U95.

c) ms = 100.02147 (79) g, νeff = 9, for the value of U95 in parentheses, the

last digit is aligned with the last digit in the previous result.

d) ms = 100.02147 (0.00079) g, νeff = 9, the value of U95 in parentheses has

the same unit of measurement as the previous results.

Note: When the extended uncertainty Up is given, for clarity, the following

description is recommended, for example: ms = (100.02147 ± 0.00079) g, where

the value after the positive/negative sign is the extended uncertainty U95 = k95uc,

wherein the combined standard uncertainty uc(ms) = 0.35 g, the degree of

freedom νeff = 9, the coverage factor kp = t95(9) = 2.26, so it has an coverage

interval with an coverage probability of 95%.

Note: When the first digit of the effective digits of uc(y) and U is 1 or 2, it shall

generally give two significant digits.

For each uncertainty component u(xi) or ui(y) in the evaluation process, in order

to avoid the uncertainty due to rounding off error, it may appropriately reserve

some more digits.

5.3.8.2 When the calculated uc(y) and U have too many digits, the routine

rounding rule is generally used to round off the data to the required valid number.

For the rounding rule, see GB/T 8170-2008 “Numerical rounding rules and

expression and judgment of limit values”. Sometimes the numbers after the last

digit of the uncertainty can be rounded up instead of rounded down.

Note: For example: U = 28.05 kHz and it needs to take two significant digits,

write it as 28 kHz after rounding off according to the regular rounding off rules.

Another example: U = 10.47 mΩ, sometimes it can be rounded up to 11 mΩ; U

= 28.05 kHz can also be written as 29 kHz.

5.3.8.3 In general, under the same measurement unit, the estimated value to

be measured shall be rounded off to the digit where its last digit is consistent to

the last digit of the uncertainty.

Note: For example: if y = 10.05762 Ω, U = 27 mΩ, because U = 0.027 Ω at the

time of reporting, y shall be rounded off to 10.058 Ω.

6 Application of measurement uncertainty

6.1 Requirements for reporting measurement uncertainty in

calibration certificate

6.1.1 In the calibration certificate, the uncertainty of the calibration value or

correction value shall generally be evaluated according to the actual situation

at each calibration.

Note:

1 The uncertainty of the calibration value or correction value...

......

(Above excerpt was released on 2020-07-13, modified on 2022-02-20, translated/reviewed by: Wayne Zheng et al.)

Source: https://www.chinesestandard.net/PDF.aspx/JJF1059.1-2012