Because impulsivity is a core symptom of hyperactive–inattentive symptoms, their items might overlap. Impulsivity and sensation seeking both tap the higher-order construct of ‘disinhibition’ and so their items might overlap as well. One item overlapped between the impulsivity and sensation seeking scales (“do things on the spur of the moment”), and between the impulsivity and hyperactive–inattentive symptoms scales (“do and say things without stopping to think”) and were removed.
