Guidelines for Evaluating and Expressing Uncertainty

1 Page 1 United States Department of Commerce Technology Administration National Institute of Standards and Technology NIST Technical Note 1297 1994 Edition Guidelines for Evaluating and Expressing the Uncertainty of NIST Measure... Open at page → 2 Page 2 NIST Technical Note 1297 1994 Edition Guidelines for Evaluating and Expressing the Uncertainty of NIST Measurement Results Barry N. Taylor and Chris E. Kuyatt Physics Laboratory National Institute of Standards and Techno... Open at page → 3 Page 3 National Institute of Standards and U.S. Government Printing Office For sale by the Superintendent of Technology Washington: 1994 Documents Technical Note 1297 U.S. Government Printing Office 1994 Edition Washington, DC... Open at page → 4 Page 4 Guidelines for Evaluating and Expressing the Uncertainty of NIST Measurement Results Preface to the 1994 Edition The previous edition, which was the first, of this National Institute of Standards and Technology (NIST) Te... Open at page → 5 Page 5 Guidelines for Evaluating and Expressing the Uncertainty of NIST Measurement Results FOREWORD (to the 1993 Edition) Results of measurements and conclusions derived from them constitute much of the technical information p... Open at page → 6 Page 6 Guidelines for Evaluating and Expressing the Uncertainty of NIST Measurement Results GUIDELINES FOR EVALUATING AND EXPRESSING THE UNCERTAINTY OF NIST MEASUREMENT RESULTS 1. Introduction 1.1 In October 1992, a new policy... Open at page → 7 Page 7 Guidelines for Evaluating and Expressing the Uncertainty of NIST Measurement Results quantity appears in the mathematical model that describes the measurement process. When the corresponding quantity is used in a differe... Open at page → 8 Page 8 Guidelines for Evaluating and Expressing the Uncertainty of NIST Measurement Results Some examples of Type B evaluations are given in subsections 4.2 to 4.6. 4.2 Convert a quoted uncertainty that is a stated multiple of... Open at page → 9 Page 9 Guidelines for Evaluating and Expressing the Uncertainty of NIST Measurement Results cases be obtained from a Type A evaluation while in other cases by a Type B evaluation. NOTES 1 The uncertainty of a correction applied... Open at page → 10 Page 10 Guidelines for Evaluating and Expressing the Uncertainty of NIST Measurement Results (i.e., k = 3) defines an interval having a level of confidence greater than 99 percent. NOTE – For a quantity z described by a normal d... Open at page → 11 Page 11 Guidelines for Evaluating and Expressing the Uncertainty of NIST Measurement Results too much information rather than too little. However, when such details are provided to the users of NIST measurement results by referr... Open at page → 12 Page 12 Guidelines for Evaluating and Expressing the Uncertainty of NIST Measurement Results significant, are clearly necessary if the assigned uncertainties are to be meaningful. 8. References [1] CIPM, BIPM Proc.-Verb. Com. In... Open at page → 13 Page 13 Guidelines for Evaluating and Expressing the Uncertainty of NIST Measurement Results A.3 The combined standard uncertainty of the measurement result y, designated by u( y) and taken to c represent the estimated standard... Open at page → 14 Page 14 Guidelines for Evaluating and Expressing the Uncertainty of NIST Measurement Results Table B.1 (to be discussed below), if ν eff =8, k 95 = 2.3 rather than 2.0. In this case, and in other similar cases where ν ( y) is co... Open at page → 15 Page 15 Guidelines for Evaluating and Expressing the Uncertainty of NIST Measurement Results Table B.1 — Value of t p (ν) from the t-distribution for degrees of freedom ν that defines an interval t p (ν)to +t(ν) that encompasses... Open at page → 16 Page 16 Guidelines for Evaluating and Expressing the Uncertainty of NIST Measurement Results Appendix C NIST Technical Communications Program APPENDIX E STATEMENTS OF UNCERTAINTY ASSOCIATED WITH MEASUREMENT RESULTS A measurement... Open at page → 17 Page 17 Guidelines for Evaluating and Expressing the Uncertainty of NIST Measurement Results NIST Technical Communications Program 3) Expanded Uncertainty: Determine an expanded uncertainty U by multiplying uby a coverage factor... Open at page → 18 Page 18 Guidelines for Evaluating and Expressing the Uncertainty of NIST Measurement Results NIST Technical Communications Program iii 4. Exceptions October 1993. ISO/TAG 4 has as its sponsors the BIPM, IEC, IFCC (International... Open at page → 19 Page 19 Guidelines for Evaluating and Expressing the Uncertainty of NIST Measurement Results Appendix D Clarification and Additional Guidance As indicated in our Preface to this second (1994) edition of TN 1297, Appendix D has b... Open at page → 20 Page 20 Guidelines for Evaluating and Expressing the Uncertainty of NIST Measurement Results – measuring instrument – reference standard – location – conditions of use – time. 3 Reproducibility may be expressed quantitatively in... Open at page → 21 Page 21 Guidelines for Evaluating and Expressing the Uncertainty of NIST Measurement Results NOTE – Since the systematic error cannot be known perfectly, the compensation cannot be complete. D.1.2 As indicated in subsection D.1.... Open at page → 22 Page 22 Guidelines for Evaluating and Expressing the Uncertainty of NIST Measurement Results uncertainty,” not every estimated standard deviation is necessarily a standard uncertainty. D.1.6 Words such as “estimated” or “limits... Open at page → 23 Page 23 Guidelines for Evaluating and Expressing the Uncertainty of NIST Measurement Results Table D.2 – Uncertainty Budget: End-Gauge Calibration Source of uncertainty Standard uncertainties from random effects in the current m... Open at page → 24 Page 24 Guidelines for Evaluating and Expressing the Uncertainty of NIST Measurement Results made of the measurand Y of which the measurement result y is an estimate. Similarly, if a combined standard uncertainty is obtained fro... Open at page → 25 Page 25 Guidelines for Evaluating and Expressing the Uncertainty of NIST Measurement Results Type A) standard uncertainty obtained from the calibration certificate of the known reference standard. NOTE – The possibility of unsus... Open at page →