2602 OS1) nternational Standard 09-2092 4851903 0013061 W-10 10 INTERNATIONAL ORGANIZATION FOR STANDARDIZATION MEXAYHAPOAHAH OPIAHM3ALWS O CTAHAAPTW3ALMM-ORGANISATION INTERNATIONALE DE NORMALISATION Statistical interpretation of test results - .Estimation of the mean -- Confidence interval Interprétation statistique de réesultats d'essais - Estimation de la moyenne -- Intervalle de confiance Second edition - 1980-02-15 UDC 519.25 : 620.113 Ref. No. 1SO 2602-1980 (E) ISO2602-1980 Descriptors : statistical analysis, statistical tests, estimation, test results, mean, variance (statistics). Pricebasedon5pages onal Organization for Standardization Not for Resale on or networking permitted without license from IHS 2602-80 E06Th 290E00 1 Foreword IsoO (the International Organization for Standardization) is a worldwide federation of national standards institutes (ISO member bodies). The work of developing Inter- nationai Standards is carried out through sO technical committees. Every member body interested in a subject for which a technical committee has been set up has the and non-governmental, in liaison with IsO, also take part in the work. Draft International Standards adopted by the technical committees are circulated to the member bodies for approval before their acceptance as international Standards by the iso Council. International Standard ISO 2602 was developed by Technical Committee ISO/TC 69, Applications of statistical methods. This second edition was submitted directly to the Iso Council, in accordance with clause 5.10.1 of part 1 of the Directives for the technical work of IsO. It cancels and replaces the first edition (i.e. IS0 2602-1973), which has been approved by the member bodies of the following countries : Portugal Australia India Austria Ireland Romania Belgium Israel South Africa, Rep. of Czechoslovakia Italy Sweden Switzerland Egypt, Arab Rep. of Japan Netherlands France Thailand Germany, F.R. New Zealand United Kingdom Hungary USSR Poland No member body had expressed disapproval of the document. International Organization for Standardization, 1980 Printed in Switzerland ewith ISO No reproduction or networking permitted without license from IHS Not for Resale INTERNATIONAL STANDARD ISO 2602-1980 (E) 0-2092 E E90ET00 E06TSgh Statistical interpretation of test results - Estimation of the mean -- Confidence interval Second edition 0 Introduction of the population of results that would be obtained from a very large number of determinations, carried out under the same conditions. In the case of items with a variability, this Interna- The scope of this International Standard is limited to a special tional Standard assumes that the individuals on which the question. It concerns only the estimation of the mean of a nor- mal population on the basis of a series of tests applied to a ran- determinations are carried out constitute a random sample dom sample of individuals drawn from this population, and from the original population and may be considered as indepen- deals only with the case where the variance of the population is dent. unknown. It is not concerned with the calculation of an interval containing, with a fixed probability, at least a given fraction of The interval so calculated is called the confidence interval for the population (statistical tolerance limits). the mean. Associated with it is a confidence level (sometimes termed a confidence coefficient),which is the probability It is recalled that IS0 2854 relates to the following collection of usually expressed as a percentage, that the interval does con- tain the mean of the population. Only the 95 % and 99 % levels Standard) : are provided for in this International Standard. estimation of a mean and of the difference between two means (the variances being either known or unknown); Scope comparison of a mean with a given value and of two means with one another (the variances being either known This International Standard specifies the statistical treat