This part of IEC 60300 provides guidelines for the planning and performing of reliability tests and the use of statistical methods to analyse test data. It describes the tests related to repaired and non-repaired items together with tests for constant and non-constant failure intensity and constant and non-constant failure rate. It is applicable: – when reliability testing is called for in a contract, either specifically or by inference; – when planning a reliability test; – during a reliability test; – when analysing data from and reporting on the outcome of a reliability test. This standard also applies when a contract or test plan specifies the use of IEC statistical standards, without specific reference to a particular standard. Many different tests are performed during the development, design verification and design validation of a new product. The purpose of these tests is to discover weaknesses in the design and to undertake actions to eliminate these weaknesses and thereby improve performance, quality, safety, robustness, reliability and availability and reduce costs. This standard covers only the cases where statistical methods are used to analyse test data although the guidelines on test conditions, test planning and test documentation will be applicable to most tests. The following topics are important and although discussed in this standard are more fully dealt with in their respective standards: availability testing (see IEC 61070); testing of maintainability measures (see IEC 60706) and measures of reliability growth (see IEC 61014 and IEC 61164). This standard does not cover software testing (see IEC 61704), however it is applicable to items containing both hardware and software. This standard is therefore applicable to a wide range of products including consumer, industrial, military and aerospace applications. This part of IEC 60300 covers analysis for verification, determination, comparison and success/failure ratio evaluation. A flow chart giving guidance for planning the statistical treatment of reliability test data is shown in clause 9. Although not described in this standard, the considerations and statistical tools can be used in connection with environmental tests, accelerated step-stress tests and over-stress tests.