ISO/TR TECHNICAL REPORT 21074 First edition 2016-10-15 Application of IS0 5725 for the determination of repeatability and reproducibility of precision tests performed in standardization work for chemical analysis of steel Application de la norme ISO 5725 pour la deétermination de la répeétabilité et la reproductibilité des essais de précision réalisés en travaux de normalisation pour I'analyse chimique de I'acier Reference number IS0/TR 21074:2016(E) ISO @IS02016 IS0/TR21074:2016(E) COPYRIGHTPROTECTEDDOCUMENT IS0 2016, Published in Switzerland All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form written permission. Permission can be requested from either ISO at the address below or ISO's member body in the country of the requester. IsOcopyrightoffice Ch. de Blandonnet 8 . CP 401 CH-1214 Vernier, Geneva, Switzerland Tel. +41 22 749 01 11 Fax +41 22 749 09 47 copyright@iso.org www.iso.org ii @ IS0 2016 - All rights reserved IS0/TR 21074:2016(E) Contents Page Foreword ..iv 1 Scope 1 2 Normative references ..1 3 Terms and definitions 4 Precision test. ..1 4.1 Structure of the precision test .1 4.2 Homogeneity of samples .2 4.3 Number of laboratories and number of levels 2 5 Representation of the experimental results .2 5.1 General .2 5.2 Tableofresultsandnumberofdecimalplaces 2 5.3 Graphical representation of the data .3 5.3.1 General 3 5.3.2 Data plot. .3 6 Statistical evaluation. .4 6.1 Cochran's test .5 6.2 Grubbs'test .6 6.2.1 General .6 6.2.2 Grubbs' test for one outlier observation. .7 6.2.3 Grubbs'test for two outlier observations 6.3 Treatmentofoutlierobservations .8 6.4 Calculation of precision 6.5 Representation of the results of the statistical evaluations 9 6.6 Functions linking the level and the precision parameters .13 7 Determining smoothed precision and scope ..15 Bibliography ..16 @ IS0 2016 - All rights reserved iii