Answer: If a staff member has known a child for at least 2 months, he/she should be encouraged to complete the C-TRF, even if guessing is necessary. The user can point out to the respondent that a score of 0 does not require complete certainty that the problem does not occur, but only that the respondent does not know that it occurs - i.e., the instructions state: 0-Not True (as far as you know).