Meaning of reliability in terms of correct and incorrect clinical decisions: the art of decision making is still alive.

Examples using cut-off scores are presented to show the effects of measurement error (unreliability) on making correct and incorrect clinical decisions. These decisions are presented in terms of true positives (TPs), true negatives (TNs), false positives (FPs), and false negatives (FNs). A discussion of the difficulty in establishing reliability standards is presented.