ISO/IEC Guide 98:1993
(Main)Guide to the expression of uncertainty in measurement (GUM)
Guide to the expression of uncertainty in measurement (GUM)
Guide pour l'expression de l'incertitude de mesure (GUM)
General Information
- Status
- Withdrawn
- Publication Date
- 31-Dec-1992
- Withdrawal Date
- 31-Dec-1992
- Technical Committee
- ISO/TMBG - Technical Management Board - groups
- Drafting Committee
- ISO/TMBG - Technical Management Board - groups
- Current Stage
- 9599 - Withdrawal of International Standard
- Start Date
- 30-Sep-2008
- Completion Date
- 13-Dec-2025
Relations
- Effective Date
- 15-Apr-2008
Frequently Asked Questions
ISO/IEC Guide 98:1993 is a guide published by the International Organization for Standardization (ISO). Its full title is "Guide to the expression of uncertainty in measurement (GUM)". This standard covers: Guide to the expression of uncertainty in measurement (GUM)
Guide to the expression of uncertainty in measurement (GUM)
ISO/IEC Guide 98:1993 is classified under the following ICS (International Classification for Standards) categories: 17.020 - Metrology and measurement in general. The ICS classification helps identify the subject area and facilitates finding related standards.
ISO/IEC Guide 98:1993 has the following relationships with other standards: It is inter standard links to ISO/IEC Guide 98-3:2008. Understanding these relationships helps ensure you are using the most current and applicable version of the standard.
ISO/IEC Guide 98:1993 is available in PDF format for immediate download after purchase. The document can be added to your cart and obtained through the secure checkout process. Digital delivery ensures instant access to the complete standard document.
This May Also Interest You
This document establishes general rules for evaluating and expressing uncertainty in measurement from the shop floor to fundamental research. Therefore, the principles of this suite of documents are intended to be applicable to a broad spectrum of measurements and their applications. An overview of the parts of the GUM is given in table A.1 in Annex A. NOTE Where the acronym GUM is used in this document, it refers to the suite of documents. An individual part of the GUM is referred to by its corresponding JCGM numbering (e.g., part 6 of the GUM is JCGM GUM-6:2020). This document gives a rationale for evaluating, expressing and using measurement uncertainty (Clause 2). A brief introduction is given to measurement (Clause 3) and to the decisions involved when evaluating measurement uncertainty (Clause 4). In Clause 5, a brief description of the contents of the parts of the GUM is given. In each of these clauses, the relevant parts of the GUM are identified for further guidance.
- Guide13 pagesEnglish languagesale 15% off
This document provides guidance on developing and using a measurement model and also covers the assessment of the adequacy of a measurement model. The document is of particular interest to developers of measurement procedures, working instructions and documentary standards. The model describes the relationship between the output quantity (the measurand) and the input quantities known to be involved in the measurement. The model is used to obtain a value for the measurand and an associated uncertainty. Measurement models are also used in, for example, design studies, simulation of processes, and in engineering, research and development. This document explains how to accommodate in a measurement model the quantities involved. These quantities relate i) to the phenomenon or phenomena on which the measurement is based, that is, the measurement principle, ii) to effects arising in the specific measurement, and iii) to the interaction with the artefact or sample subject to measurement. The guidance provided is organised in accordance with a work flow that could be contemplated when developing a measurement model from the beginning. This work flow starts with the specification of the measurand (clause 6). Then the measurement principle is modelled (clause 7) and an appropriate form of the model is chosen (clause 8). The basic model thus obtained is extended by identifying (clause 9) and adding (clause 10) effects arising from the measurement and the artefact or sample subject to measurement. Guidance on assessing the adequacy of the resulting measurement model is given in clause 12. The distinction between the basic model and the (complete) measurement model in the work flow should be helpful to those readers who already have a substantial part of the measurement model in place, but would like to verify that it contains all effects arising from the measurement so that it is fit for purpose. Guidance on the assignment of probability distributions to the quantities appearing in the measurement model is given in JCGM 100:2008 and JCGM 101:2008. In clause 11, this guidance is supplemented by describing how statistical models can be developed and used for this purpose. When using a measurement model, numerical problems can arise including computational effects such as rounding and numerical overflow. It is demonstrated how such problems can often be alleviated by expressing a model differently so that it performs well in calculations. It is also shown how a reformulation of the model can sometimes be used to eliminate some correlation effects among the input quantities when such dependencies exist. Examples from a number of metrology disciplines illustrate the guidance provided in this document.
- Guide96 pagesEnglish languagesale 15% off
ISO/IEC Guide 98-4:2012 provides guidance and procedures for assessing the conformity of an item (entity, object or system) with specified requirements. The item might be, for example, a gauge block, a grocery scale or a blood sample. The procedures can be applied where the following conditions exist: the item is distinguished by a single scalar quantity (a measurable property) defined to a level of detail sufficient to be reasonably represented by an essentially unique true value; an interval of permissible values of the property is specified by one or two tolerance limits; the property can be measured and the measurement result expressed in a manner consistent with the principles of the GUM, so that knowledge of the value of the property can be reasonably described by (a) a probability density function, (b) a distribution function, (c) numerical approximations to such functions, or (d) a best estimate, together with a coverage interval and an associated coverage probability. The procedures developed in this document can be used to realize an interval, called an acceptance interval, of permissible measured values of the property of interest. Acceptance limits can be chosen so as to balance the risks associated with accepting non-conforming items (consumer's risk) or rejecting conforming items (producer's risk). Two types of conformity assessment problems are addressed. The first is the setting of acceptance limits that will assure that a desired conformance probability for a single measured item is achieved. The second is the setting of acceptance limits to assure an acceptable level of confidence on average as a number of (nominally identical) items are measured. Guidance is given for their solution. This document contains examples to illustrate the guidance provided. The concepts presented can be extended to more general conformity assessment problems based on measurements of a set of scalar measurands. The audience of this document includes quality managers, members of standards development organizations, accreditation authorities and the staffs of testing and measuring laboratories, inspection bodies, certification bodies, regulatory agencies, academics and researchers.
- Guide49 pagesEnglish languagesale 15% off
- Guide49 pagesEnglish languagesale 15% off
- Guide56 pagesFrench languagesale 15% off
- Guide56 pagesFrench languagesale 15% off
ISO/IEC Guide 98-3:2008/Suppl.2:2011 is concerned with measurement models having any number of input quantities and any number of output quantities. The quantities involved might be real or complex. Two approaches are considered for treating such models. The first approach is a generalization of the GUM uncertainty framework. The second is a Monte Carlo method as an implementation of the propagation of distributions. Appropriate use of the Monte Carol method would be expected to provide valid results when the applicability of the GUM uncertainty framework is questionable. For a prescribed coverage probability, ISO/IEC Guide 98-3:2008/Suppl.2:2011 can be used to provide a coverage region for the output quantities of a multivariate model, the counterpart of a coverage interval for a single scalar output quantiy. The provision of coverage regions includes those taking the form of a hyper-ellipsoid or a hyper-rectangle. These coverage regions are produced from the results of the two approaches described here. A procedure for providing an approximation to the smallest coverage region, obtained from results provided by the Monte Carol method, is also given. Detailed examples to illustrate the guidance are provided.
- Guide73 pagesEnglish languagesale 15% off
ISO/IEC Guide 98-3/Suppl.1:2008 provides a general numerical approach, consistent with the broad principles of the Guide to the expression of uncertainty in measurement (GUM), for carrying out the calculations required as part of an evaluation of measurement uncertainty. The approach applies to arbitrary models having a single output quantity where the input quantities are characterized by any specified probability density functions (PDFs). ISO/IEC Guide 98-3/Suppl.1:2008 is primarily concerned with the expression of uncertainty in the measurement of a well-defined physical quantity-the measurand-that can be characterized by an essentially unique value. It provides guidance in situations where the conditions for the GUM uncertainty frameworkare not fulfilled, or it is unclear whether they are fulfilled. It can be used when it is difficult to apply the GUM uncertainty framework, because of the complexity of the model, for example. Guidance is given in a form suitable for computer implementation. ISO/IEC Guide 98-3/Suppl.1:2008 can be used to provide (a representation of) the PDF for the output quantity from which (a) an estimate of the output quantity, (b) the standard uncertainty associated with this estimate, and (c) a coverage interval for that quantity, corresponding to a specified coverage probability, can be obtained. For a prescribed coverage probability, it can be used to provide any required coverage interval, including the probabilistically symmetric coverage interval and the shortest coverage interval. ISO/IEC Guide 98-3/Suppl.1:2008 applies to input quantities that are independent, where each such quantity is assigned an appropriate PDF, or not independent, i.e. when some or all of these quantities are assigned a joint PDF. Detailed examples illustrate the guidance provided.
- Guide88 pagesEnglish languagesale 15% off
ISO/IEC Guide 98-3:2008 is a reissue of the 1995 version of the Guide to the Expression of Uncertainty in Measurement (GUM), with minor corrections. This Guide establishes general rules for evaluating and expressing uncertainty in measurement that can be followed at various levels of accuracy and in many fields - from the shop floor to fundamental research. The principles of this Guide are intended to be applicable to a broad spectrum of measurements, including those required for: maintaining quality control and quality assurance in production; complying with and enforcing laws and regulations; conducting basic research, and applied research and development, in science and engineering; calibrating standards and instruments and performing tests throughout a national measurement system in order to achieve traceability to national standards; developing, maintaining, and comparing international and national physical reference standards, including reference materials.
- Guide120 pagesEnglish languagesale 15% off
- Guide120 pagesEnglish languagesale 15% off
- Guide121 pagesFrench languagesale 15% off
ISO/IEC Guide 99:2007 provides a set of definitions and associated terms, in English and French, for a system of basic and general concepts used in metrology, together with concept diagrams to demonstrate their relations. Additional information is given in the form of examples and notes under many definitions. This Vocabulary is meant to be a common reference for scientists and engineers, as well as teachers and practitioners, involved in planning or performing measurements, irrespective of the level of measurement uncertainty and irrespective of the field of application. It is also meant to be a reference for governmental and inter-governmental bodies, trade associations, accreditation bodies, regulators and professional societies.
- Guide100 pagesEnglish languagesale 15% off
- Guide106 pagesEnglish and French languagee-Library read for×1 day
- Guide100 pagesRussian languagesale 15% off
- Guide – translation197 pagesSlovenian, English and French languagee-Library read for×1 day
- Draft137 pagesEnglish languagesale 15% off
1.1 This document - amplifies the general principles for designing experiments for the numerical estimation of the precision of measurement methods by means of a collaborative interlaboratory experiment, - provides a detailed practical description of the basic method for routine use in estimating the precision of measurement methods, and - provides guidance to all personnel concerned with designing, performing or analysing the results of the tests for estimating precision. NOTE Modifications to this basic method for particular purposes are given in other parts of ISO 5725. 1.2 It is concerned exclusively with measurement methods which yield measurements on a continuous scale and give a single value as the test result, although this single value can be the outcome of a calculation from a set of observations. 1.3 It assumes that in the design and performance of the precision experiment, all the principles as laid down in ISO 5725-1 are observed. The basic method uses the same number of test results in each laboratory, with each laboratory analysing the same levels of test sample; i.e. a balanced uniform-level experiment. The basic method applies to procedures that have been standardized and are in regular use in a number of laboratories. 1.4 The statistical model of ISO 5725-1:2023, Clause 5, is accepted as a suitable basis for the interpretation and analysis of the test results, the distribution of which is approximately normal. 1.5 The basic method, as described in this document, (usually) estimates the precision of a measurement method: a) when it is required to determine the repeatability and reproducibility standard deviations as defined in ISO 5725-1; b) when the materials to be used are homogeneous, or when the effects of heterogeneity can be included in the precision values; c) when the use of a balanced uniform-level layout is acceptable. 1.6 The same approach can be used to make a preliminary estimate of precision for measurement methods which have not reached standardization or are not in routine use.
- Standard67 pagesEnglish languagesale 15% off
- Standard71 pagesFrench languagesale 15% off
- 17-Dec-2025
- 03.120.30
- 17.020
- ISO/TC 69/SC 6
This document presents methods for determining the critical value of the response variable and the minimum detectable value in Poisson distribution measurements. It is applicable when variations in both the background noise and the signal are describable by the Poisson distribution. The conventional approximation is used to approximate the Poisson distribution by the normal distribution consistent with ISO 11843-3 and ISO 11843-4. The accuracy of the normal approximation as compared to the exact Poisson distribution is discussed in Annex B.
- Standard21 pagesEnglish languagesale 15% off
- 22-Oct-2025
- 03.120.30
- 17.020
- ISO/TC 69/SC 6
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.
Loading comments...