A form of bias that occurs in the study of diagnostic test validity when the test result influences the decision whether to use the gold standard.
Note: This bias can substantially distort the estimation of the validity of the test studied. It can be avoided if all the eligible subjects are consecutively verified using the gold standard, regardless of the result of the test studied, or if the subjects are selected on the basis of the results of the gold standard, before the results of the test studied are known.
Syn.: verification bias.