You just don't want errors when you're dealing with blood, or the blood bank refrigerators in which it's stored.

“[People] cannot eliminate the errors simply by telling themselves to do better and deciding not to commit them.”  Perhaps not a surprising statement, but one whose implications can be pretty far-reaching.  The statement comes from a document entitled “Mistake-Proofing the Design of Health Care Processes.”  The logical argument is that if you’re in an environment where mistakes are critical, and mistakes will happen even with careful, attentive people, then you need to do something to make mistakes impossible: mistake-proof design.  For example, blood bank refrigerators “equipped with temperature monitors that sound an alarm if and when the temperature is out of the safety range.”