Cannabis initiation was defined as the first time the participant ever used cannabis with age of onset recorded as the earliest age this first occurred. For those who endorsed ever using cannabis at more than one assessment, Cronbach alpha for age of first cannabis initiation was 0.90, indicating high test-retest reliability across waves 1, 3, and 4. As there is no standard definition of early cannabis initiation, we chose the lowest third of the age at initiation distribution (age 15 or younger) to represent early use relative to same sex peers. First CUD symptom was coded positive for individuals who endorsed one or more symptom of cannabis abuse or dependence with age at first CUD symptom derived from reported age(s) that each endorsed symptom was first experienced.
