This book is about the measurement and prediction of the reliability behaviour of systems of physical items. It is not specifically concerned with human factors with safety analysis as such, although some of the techniques discussed are adaptable to these purposes. A machine or an electronic circuit exemplifies a system. Each machine or circuit may also be treated as an item in a larger system. However, this does not reduce it suddenly to basic component status; it remains complex and can only be treated as unitary under definable restrictions. In particular, the effects of maintenance and...