Take the following as truth: Bias detection methods may be inadequate; may fail to take into account diverse views about program goals and purposes; competence of all on-site observers may not be sufficiently high; can be costly due to study size; the demands of data management, data quality control, validation procedures, and analytic model (within site, cross site, etc.) may lead to cutting too many corners to maintain quality
Then the following statement: "Bias detection methods are foolproof and never fail." is true, false, or inconclusive?