Table 1.

Concept Exclusion Criteria for the Different Sources

Source	Elimination Rule
MRREL	Relationship type = “can be qualified by”*
MRREL	Relationship type = “is an allowed qualifier for”*
MRCOC	Number of co-occurrence < 3
MRCOC	Co-occurrence type = “qualification”*
QRYLOG	Number of co-occurrence < 3
ALL Sources	Related concept name > 35 characters
ALL Sources	Related concept is a “stop concept”†

^*The qualification relationship appears to be both overly broad and inscrutable.

^†We maintained a list of “stop concepts” that we have found to be unusually unhelpful as query concepts. Examples from this “stop concept” list include the concepts with the names “Preposition For,” “Of,” and “With.”