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
Diverse views about program goals may foil bias detection methods.
Bias detection methods are foolproof and never fail.
Yesterday at the press conference Clinton expressed concern that people think things are going very poorly, but still have faith in the system.
The dog is after a ball.
Tuppence waited for the previous speaker to finish speaking before sharing her opinion.
Two kids are eating cereal.
The woman taking the picture is standing up
It is a lot for a women, based on what she did.