BS EN 61710:2013
$198.66
Power law model. Goodness-of-fit tests and estimation methods
Published By | Publication Date | Number of Pages |
BSI | 2013 | 60 |
IEC 61710:2013 specifies procedures to estimate the parameters of the power law model, to provide confidence intervals for the failure intensity, to provide prediction intervals for the times to future failures, and to test the goodness-of-fit of the power law model to data from repairable items. It is assumed that the time to failure data have been collected from an item, or some identical items operating under the same conditions (e.g. environment and load). This second edition cancels and replaces the first edition, published in 2000, and constitutes a technical revision. The main changes with respect to the previous edition are listed below: the inclusion of an additional Annex C on Bayesian estimation for the power law model. Keywords: power law model, Bayesian estimation, reliability of repairable items
PDF Catalog
PDF Pages | PDF Title |
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6 | English CONTENTS |
9 | INTRODUCTION |
10 | 1 Scope 2 Normative references 3 Terms and definitions 4 Symbols and abbreviations |
11 | 5 Power law model |
12 | 6 Data requirements 6.1 General 6.1.1 Case 1 – Time data for every relevant failure for one or more copies from the same population 6.1.2 Case 1a) – One repairable item Figures Figure 1 – One repairable item |
13 | 6.1.3 Case 1b) – Multiple items of the same kind of repairable item observed for the same length of time 6.1.4 Case 1c) – Multiple repairable items of the same kind observed for different lengths of time Figure 2 – Multiple items of the same kind of repairable item observed for same length of time |
14 | 6.2 Case 2 – Time data for groups of relevant failures for one or more repairable items from the same population 6.3 Case 3 – Time data for every relevant failure for more than one repairable item from different populations Figure 3 – Multiple repairable items of the same kind observedfor different lengths of time |
15 | 7 Statistical estimation and test procedures 7.1 Overview 7.2 Point estimation 7.2.1 Case 1a) and 1b) – Time data for every relevant failure |
16 | 7.2.2 Case 1c) – Time data for every relevant failure |
17 | 7.2.3 Case 2 – Time data for groups of relevant failures |
18 | 7.3 Goodness-of-fit tests 7.3.1 Case 1 – Time data for every relevant failure |
19 | 7.3.2 Case 2 – Time data for groups of relevant failures |
20 | 7.4 Confidence intervals for the shape parameter 7.4.1 Case 1 – Time data for every relevant failure |
21 | 7.4.2 Case 2 – Time data for groups of relevant failures |
22 | 7.5 Confidence intervals for the failure intensity 7.5.1 Case 1 – Time data for every relevant failure 7.5.2 Case 2 – Time data for groups of relevant failures |
23 | 7.6 Prediction intervals for the length of time to future failures of a single item 7.6.1 Prediction interval for length of time to next failure for case 1 – Time data for every relevant failure |
24 | 7.6.2 Prediction interval for length of time to Rth future failure for case 1 – Time data for every relevant failure |
25 | 7.7 Test for the equality of the shape parameters β1,β 2, …, β k 7.7.1 Case 3 – Time data for every relevant failure for two items from different populations |
26 | 7.7.2 Case 3 – Time data for every relevant failure for three or more items from different populations |
27 | Tables Table 1 – Critical values for Cramer-von-Mises goodness-of-fit testat 10 % level of significance |
28 | Table 2 – Fractiles of the Chi-square distribution |
29 | Table 3 – Multipliers for two-sided 90 % confidence intervals for intensity function for time terminated data |
30 | Table 4 – Multipliers for two-sided 90 % confidence intervals for intensity function for failure terminated data |
31 | Table 5 – 0,95 fractiles of the F distribution |
32 | Annex A (informative) The power law model – Background information |
33 | Annex B (informative) Numerical examples Table B.1 – All relevant failures and accumulated times for software system |
34 | Figure B.1 – Accumulated number of failures against accumulated timefor software system Figure B.2 – Expected against observed accumulated times to failurefor software system |
35 | Table B.2 – Calculation of expected accumulated times to failure for Figure B.2 |
36 | Table B.3 – Accumulated times for all relevant failuresfor five copies of a system (labelled A, B, C, D, E) Table B.4 – Combined accumulated times for multiple items of the same kind of a system |
37 | Figure B.3 – Accumulated number of failures against accumulated timefor five copies of a system |
38 | Table B.5 – Accumulated operating hours to failure for OEM product from vendors A and B |
39 | Figure B.4 – Accumulated number of failures against accumulated time for an OEM product from vendors A and B |
40 | Figure B.5 – Accumulated number of failures against time for generators Table B.6 – Grouped failure data for generators |
41 | Figure B.6 – Expected against observed accumulated number of failures for generators |
42 | Table B.7 – Calculation of expected numbers of failures for Figure B.6 |
43 | Annex C (informative) Bayesian estimation for the power law model |
44 | Table C.1 – Strengths and weakness of classical and Bayesian estimation |
48 | Table C.2 – Grid for eliciting subjective distribution for shape parameter β Table C.3 – Grid for eliciting subjective distribution for expected number of failures parameter η |
49 | Figure C.1 – Plot of fitted Gamma prior (6,7956, 0,0448) for the shape parameter of the power law model Figure C.2 – Plot of fitted Gamma prior (17,756 6, 1447,408) for the expected number of failures parameter of the power law model |
50 | Table C.4 – Comparison of fitted Gamma and subjective distributionfor shape parameter β Table C.5 – Comparison of fitted Gamma and subjective distribution for expected number of failures by time T = 20 000 h parameter η |
51 | Table C.6 – Times to failure data collected on system test |
52 | Table C.7 – Summary of estimates of power law model parameters |
53 | Figure C.3 – Subjective distribution of number of failures |
55 | Table C.8 – Time to failure data for operational system |
56 | Figure C.4 – Plot of the posterior probability distribution for the number of future failures, M |
57 | Figure C.5 – Plot of the posterior cumulative distribution for the number of future failures, M |
58 | Bibliography |