ISO INTERNATIONAL STANDARD 14802 First edition 2012-07-15 Corrosion of metals and alloys Guidelines for applying statistics to analysis of corrosion data Corrosion des metaux et alliages - Lignes directrices pour I'application des statistiques a I'analyse des donnees de corrosion Reference number ISO 14802:2012(E) ISO @ISO2012 I by IHS under lic No reproduction or networking permitted without license from IHS Not for Resale ISO14802:2012(E) COPYRiGHTPROTECTEDDOCUMENT ISO 2012 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 [email protected] Web www.iso.org Published in Switzerland @ ISO 2012 - All rights reserved or networking permited withoutlicense from IHS Not for Resale ISO 14802:2012(E) Contents Page Foreword .iv 1 Scope 2 Significance and use 3 Scatter of data. 3.1 Distributions 3.2 Histograms.... 3.3 Normal distribution. 3.4 Normal probability paper. 3.5 Other probability paper... 3.6 Unknown distribution. 3.7 Extreme value analysis. 3 3.8 Significant digits.. 3.9 Propagation of variance 3.10 Mistakes. 4 Central measures .. 4.1 Average.. 4.2 Median.... 4.3 Which to use... 5 Variability measures 5.1 General. 5.2 Variance. 4 5.3 Standard deviation... 5.4 Coefficient of variation. 5 5.5 Range. 5 5.6 Precision 5.7 Bias 6 Statistical tests.. 6.1 Null hypothesis . 6.2 Degrees of freedom 6.3 6.4 F-test. 6.5 Correlation coefficient 6.6 Sign test... 9 6.7 Outside count.. 9 7 Curve fitting- - Method of least squares 7.1 Minimizing variance. 9 7.2 Linear regression - 2 variables 9 7.3 Polynomial regression... 10 7.4 Multiple regression . 10 8 Analysis of variance .. 11 8.1 Comparison of effects. 11 8.2 The two-level factorial design 11 9 Extreme value statistics .. 11 9.1 Scope of this clause .. 11 9.2 Gumbel distribution and its probability paper 12 9.3 Estimation of distribution parameters. 13 9.4 15 9.5 Other topics . 15 Annex A (informative) Sample calculations. ..46 Bibliography .60 ili ted without licensefrom IHS Not for Resale