A test in which a sample or population of items is subjected to stated stress conditions for specified times with stated failure or success criteria, in order to determine its reliability characteristics. The data from such tests will provide information giving failure rate and mean life of the item. The reliability of most semiconductor devices, etc. is so great that accelerated life tests and step-stress life tests are employed to avoid unnecessarily long tests. Truncated tests are those terminated after a predetermined time or a predetermined number of failures or a combination of these. A screening test is a test designed to remove unsatisfactory items or those likely to exhibit early failures. This is sometimes called burn-in (see failure rate).