Why: HASS testing is to verify product performance is on target and has not shifted toward inferior performance in the manufacturing process. Note that higher stresses often produce accelerated failures out of proportion to the increased stress applied.
When: Products are periodically screened by HASS to verify no shifts have occurred in the manufacturing process.
Where: HASS tests are performed as a quality assurance test in manufacturing facilities to learn what you don't know about each product as it is faster than a simple burn-in test. If 100% of the finished goods do not receive HASS, as when only a percentage of the product is screened by HASS this is called a highly accelerated stress audit (HASA).
These definitions are written by H. Paul Barringer and are also posted on his web site at www.barringer1.com