Some of these differences are unlikely to explain the lower prevalence systematically observed in the CTADS.
In particular, the new format of the CTADS may further influence the responses of respondents with the inclusion of alcohol- and drug-related issues.
For instance, the CCHS and CTADS use a slightly different sampling frame: the CCHS used a combination of an area frame (40%-50%), lists of telephone numbers (40%-50%) and randomdigit dialing (RDD) ([+ or -] 1%) to cover their sampling frame while the CTUMS/CTADS used an RDD-only strategy.
Cross-sectional data were obtained from the 2013 CTADS which was administered as a random digit dialing (RDD) survey; telephone numbers were generated using the Household Survey Frame Service and interviews took place over the telephone.
The 2013 CTADS collected information on sex, age, region of residence, and population density of residence.
CTADS included five questions about possible problems encountered by cannabis users: 1) "During the past 3 months how often have you ever had a strong desire or urge to use marijuana?
A binary variable was also derived for ranking individuals along risk levels for problematic cannabis consumption using the WHO ASSIST tool embedded in CTADS.