sentence1: 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
sentence2: Programs that provide aid to the poor are most likely to fail bias tests.