with the original TLFB, the ABCD TLFB utilizes memory cues, such as holidays and personal events elicited from the youth that may improve substance use recall (e.g., sleepovers, birthdays, parties, holidays) and these are populated onto the web-based calendar. The site-based research assistant collaborates with the youth to review each week of potential use, and all substance use within that week. (See Fig. 1a–c for pictures of on-line calendar and substance use interface.) To facilitate accurate labeling and dose quantification, if a youth endorses using a substance, the research staff presents visual pictures depicting standard units and modes of use (e.g., standard drink sizes for alcohol; for some substances, “times used” or number of occasions are used as the standard units; research assistants inform participants that this measures separate occasions used per day and that an occasion is defined as a period when you used a drug and then took a break and that the setting may change between occasions (See Supplemental Material for TLFB Standard Unit Visual Slides). As outlined in the next section, follow-up questions assess routes of administration (cannabis concentrates, e-cigarettes, cocaine, methamphetamine, heroin), flavoring (cigarettes), typical dosing (e-cigarettes), product content/potency (smoked cannabis, cannabis concentrate, cannabis-infused alcohol
