PDS

19 Quality and reliability

Although quality and reliability are hard to quantify, you must put figures on them nonetheless. Values for mean time before failure (MTBF) and mean time to repair (MTTR) are often given in electronics, but these measures are not so suitable for mechanical, hydraulic, or other less predictable components. Here you could refer to the company's records for statistical data on the performance of similar products in the past. British Standards 5750 and 5760 also give helpful guidance. See references 6, 7 and 8.