BS IEC 61710:2000 pdf download-Power law model Ð Goodness-of-fit tests and estimation methods.
7 Statistical estimation and test procedures 7.1 Overview In case 1 – time data for every relevant failure – the formulae given for failure terminated data assume one repaired item, that is 1 = k . All output results correspond to that item. The formulae given for time terminated data assume k copies of the item observed for the same length of time. If there is only one repaired item then 1 = k . The point estimation procedures for all the aforementioned cases are given in 7.2.1. The appropriate procedures for the case when all copies are observed for different lengths of time are given in 7.2.2. Procedures for the case of time data for groups of relevant failures are given in 7.2.3. An appropriate goodness-of-fit test, as described in 7.3 shall be performed after the parameter estimation procedures of 7.2. Note that these tests, and the procedures given in 7.4 to 7.7 for constructing interval estimates and carrying out statistical tests, distinguish only between the cases of time data for every relevant failure (i.e. all instances of case 1 data – 1a), 1b) and 1c)) and time data for groups of relevant failures (i.e. case 2). NOTE The inference procedures that follow provide approximate estimates in some circumstances and so caution is required if they are to be applied to very small samples of data.
7.3.2.2 Graphical procedure When the data set consists of known time intervals, each containing a known number of failures, the graphical procedure described below may be used to obtain additional information about the correspondence between the model and the data. This involves plotting the expected number of failures against those observed at each endpoint. Further details of the approach are given in annex A.