Hours high as a proxy for marijuana use quantity in intensive longitudinal designs

Measuring marijuana use quantity in survey research is complicated due to wide variation in the types (e.g., flower, edibles) and potency of marijuana products and in the modes (e.g., smoking, dabbing) used to consume products. There is currently no gold standard marijuana use quantity measure for survey research. This study examined whether number of hours high can be used as a proxy for marijuana use quantity in survey research, particularly in intensive longitudinal designs. Participants came from a community sample of young adults participating in a longitudinal study on simultaneous alcohol and marijuana use that used a longitudinal measurement-burst design in which participants completed surveys on up to 14 consecutive days in up to five bursts across nearly two calendar years. Those who reported using marijuana on at least one sampled day were included in present analyses (N = 379; M = 21.6; 50.7 % female). Hypotheses were tested using Poisson multilevel models and a logistic regression. Within persons, mode-specific marijuana use quantity variables predicted same-day number of hours high indicating evidence of initial criterion validity. In turn, hours high predicted same-day negative marijuana-related consequences indicating evidence of proximal predictive validity. Between persons, participants' average number of hours high was positively associated with their odds of possible cannabis use disorder following the last burst demonstrating distal predictive validity. Number of hours high may be a parsimonious proxy for measuring marijuana use quantity (regardless of mode of use) in survey research, particularly in intensive longitudinal designs.