It is possible for a recall to meet minimum criteria, but
still not be acceptable for use in further research.
Interviewers assess whether or not they believe each 24-h
recall is reliable based on their knowledge of how the
interview transpired, and they provide reasons whenever an
assessment of ‘‘unreliable’’ is made. Reasons vary, but
‘‘unreliable’’ may result if a sample person has been
uncooperative, or could not fully participate because of
memory or other difficulties and a suitable proxy was not
available. Each 24-h recall marked as unreliable is reviewed
by survey nutritionists at FSRG who judge the usability of
the data.