quality assurance
/ KWOL-ih-tee uh-SHOOR- uns /
Think of the difference between an airline tasting each meal before it's served and the airline's whole system that decides which kitchens are approved, how staff are trained, how recipes are documented and how complaints get followed up. Quality assurance is that second, bigger thing for a lab: the planned framework that makes good results happen, rather than the spot-checks themselves.
Quality assurance is the overarching system of planned activities — written procedures, staff training, equipment calibration schedules, document control, audits and management review — designed to give confidence that the lab's results will be reliable. It builds the structure within which day-to-day quality control checks are carried out and shown to be enough.
It matters because reliable data is not an accident; it comes from a culture and a system that anticipate where things can go wrong and put safeguards in place beforehand. The honest caveat is that quality assurance is mostly invisible in any single result — you cannot see it in a number — yet without it even a perfect method run by careful people slowly drifts out of control.
A lab's quality-assurance system requires that every method be validated, every instrument calibrated on a fixed schedule, every analyst trained and signed off, and the lab audited yearly — so that any single result can be traced back through documents that prove it was made correctly.
The planned system that makes reliable results happen, not the spot-checks themselves.
A memory aid: quality assurance is about building quality in (prevention, system, planning), while quality control is about catching defects (detection, testing, the bench). You need both, and quality control lives inside quality assurance.