Table 1.

List of assessments.

Drug history: for cannabis only, tobacco only, and tobacco mixed with cannabis	Ever used? (yes/no) Age of first use? (in years) Used in the last 12 months? (yes/no) Number of days used in the last 30 days?a Used in the last 7 days? (yes/no)
Route of administration	Which is the most common way you currently use cannabis? (Select one): (a) Smoked in joint with tobacco (b) Smoked in blunt with tobacco (c) Smoked in pipe with tobacco (d) Smoked in bong/water pipe with tobacco (e) Smoked in joint without tobacco (f) Smoked in blunt without tobacco (g) Smoked in pipe without tobacco (h) Smoked in bong/water pipe without tobacco (i) Smoked using “bucket bong” (j) Smoked using hot knife (k) Using vaporizer (l) Eating it in food (m) Drinking in tea/infusion (n) Other
Impact of drug use	Typically, on a day that you use cannabis, how much cannabis do you use? (in grams) How would you rate the overall negative effects when high (rated between 1 and 10) How would you rate the overall pleasurable effect when high (rated between 1 and 10)
Intention to use less of each drug: for cannabis only and tobacco only	Would you like to use less cannabis/tobacco over the next 12 months? (yes/unsure/no) Would you like help to use less cannabis/tobacco over the next 12 months? (yes/unsure/no) Are you planning to seek help to use less cannabis/tobacco over the next 12 months? (yes/unsure/no)

The structure of the GDS is personalized based on this drug use history; therefore, if the respondent has never used cannabis, for example, they would not have the opportunity to answer questions regarding cannabis.

^aUsed in Table 3 as DPM cannabis, tobacco, and tobacco with cannabis.