63923-7

In the past, have you ever made a serious attempt to quit smoking That is, have you stopped smoking for at least one day or longer because you were trying to quit [PLCO]

In the past, have you ever made a serious attempt to quit smoking That is, have you stopped smoking for at least one day or longer because you were trying to quit, a finding in the patient by PLCO, an ordinal result. PhenX measures.