IEC TR 63250:2021

IEC TR 63250 ®
Edition 1.0 2021-06
TECHNICAL
REPORT
Household and similar electrical appliances – Method of measuring
performance – Assessment of repeatability, reproducibility and uncertainty
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IEC TR 63250 ®
Edition 1.0 2021-06
TECHNICAL
REPORT
Household and similar electrical appliances – Method of measuring

performance – Assessment of repeatability, reproducibility and uncertainty

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 97.030 ISBN 978-2-8322-9939-5

– 2 – IEC TR 63250:2021 © IEC 2021
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 7
4 Determination of standard deviations . 10
4.1 General . 10
4.2 Repeatability standard deviation . 10
4.3 Reproducibility standard deviation . 10
5 Assessment of repeatability, reproducibility, and uncertainty of a measurement
method . 11
5.1 Purpose . 11
5.2 Requirements . 11
5.3 Expression of repeatability and reproducibility . 12
5.4.1 The importance of the uncertainty . 12
5.4.2 Methods to estimate uncertainty . 12
5.4.3 Expanded uncertainty calculation . 13
6 Scrutiny of results for consistency and outliers . 14
6.1 Purpose . 14
6.2 Graphical consistency technique (Mandel's h and k statistics) . 14
6.2.1 Inter-laboratory consistency statistic h . 14
6.2.2 Intra-laboratory consistency statistic k . 14
6.2.3 Evaluation . 14
6.3 Numerical outlier technique . 15
6.3.1 Cochran's C test . 15
6.3.2 Grubbs' test . 15
6.3.3 Evaluation . 15
7 Data to be reported for assessing the repeatability, reproducibility and uncertainty
of a test method. 16
Annex A (informative)  Example of bottom-up analysis . 17
A.1 General . 17
A.2 Temperature measurement system . 17
A.2.1 General . 17
A.2.2 Calibration of thermocouples . 17
A.2.3 Calibration of the DAQ system . 17
A.3 Uncertainty temperature measurement . 17
A.4 Analysis of each component in the uncertainty formulation, example
thermocouple simulator . 19
Annex B (informative)  Guidance on how to conduct round robin tests for household
and similar electrical appliances . 21
B.1 General . 21
B.2 Scope . 21
B.3 Process and responsibilities . 22
B.3.1 Process . 22
B.3.2 Responsibilities . 23
B.4 Testing laboratories . 23

B.4.1 Potential laboratories . 23
B.4.2 Announcement. 23
B.4.3 Selection of laboratories . 24
B.4.4 Final list of laboratories . 24
B.5 Transportation of the product . 24
B.5.1 Logistics . 24
B.5.2 Packaging. 24
B.6 Test . 24
B.6.1 Performance of test . 24
B.6.2 Laboratory visit . 25
B.6.3 Transmission of result . 25
B.7 Analysis, report and termination . 25
B.7.1 Analysis . 25
B.7.2 Report . 25
B.7.3 Termination and publication of final external report . 26
Annex C (informative)  Example of a round robin test and its analysis. 27
C.1 General . 27
C.2 Standard deviations and assessment of repeatability and reproducibility . 27
C.3 Scrutiny of results for consistency and outliers. 29
C.3.1 Example of Mandel's h and k statistics . 29
C.3.2 Example of numerical outlier test . 29
Annex D (informative) Example of expression of results . 32
Bibliography . 33

Figure 1 – Visualisation of straggler and outlier of Cochrane value . 16
Figure C.1 – Mandel's h statistics. 30
Figure C.2 – Mandel's k statistics . 31

Table A.1 – Description of uncertainty parameters . 18
Table A.2 – Measuring a temperature of −23 °C at a climate room temperature
between 16 °C to 32 °C . 19
Table A.3 – Expanded uncertainty in measured temperature (U(T), k = 2) at a room
temperature in the range of 16 °C to 32 °C and a lab temperature between 14 °C and

32 °C . 19
Table A.4 – Calibration results of the simulator . 20
Table C.1 – Measurement results . 27
Table C.2 – Standard deviations, repeatability and reproducibility . 28
Table C.3 – Mandel's h and k statistics . 29
Table C.4 – Cochran's test C and Grubbs' test G . 29
Table C.5 – Cochran's test C and Grubbs' test G summary . 30

– 4 – IEC TR 63250:2021 © IEC 2021
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
HOUSEHOLD AND SIMILAR ELECTRICAL APPLIANCES –
METHOD OF MEASURING PERFORMANCE – ASSESSMENT OF
REPEATABILITY, REPRODUCIBILITY AND UNCERTAINTY

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
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3) IEC Publications
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