Statistical QC practices are critical for assuring test results are correct. QC is like Safety QC practices, like safety practices, are recognized to be important if something bad happens, but they seems to be a waste of time and effort when things are working okay. The key to their success is advance planning, anticipation of what might go wrong, warnings when things are going wrong, and a planned course of action to respond to a problem and minimize the damage. Many people agree that a smoke detector is necessary, but still think it's a waste of time to have an evacuation plan, fire drills, and training with fire extinguishers, at least until such time as a real fire occurs. Then it suddenly becomes relevant, and hopefully its not too late to read the yellow emergency response guide posted in the laboratory.
Safety is part of basic training in the laboratory.
So is quality control. We need to keep at it if we are to maintain a good program, prevent unfortunate events, detect problems, and respond quickly when they occur. We are required to periodically review our safety procedures and participate in planned drills. We also need to review our QC procedures and be sure they accomplish what they're supposed to - they're supposed to detect errors, but they shouldn't give a lot of false alarms that wastes time and effort. Here's a minimum that everyone should understand.