"Users should be aware of a number of differences between CCHS and CTADS. CCHS collects information from respondents aged 12 and over, CTADS collects information from respondents aged 15 and over; the two surveys use different sampling frames; the annual sample for CTADS is 20,000 compared to 65,000 for CCHS; in CCHS, smoking questions are asked in the context of a wide range of health-related behaviours whereas in CTADS, all questions are related to the use of multiple products and substances with addictive properties." (6)
Some of these differences are unlikely to explain the lower prevalence systematically observed in the CTADS. First, the lower age group included in the CCHS (12+ versus 15+) should not produce a higher estimate because smoking rates at ages 12-14 years are significantly lower than those in the rest of the population.
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.
in the CCHS and CTUMS/ CTADS? Coverage Coverage issues, either CCHS uses this Target population due to over-or under- operational definition Sampling frame coverage, may result in for non-eligible estimates inferring to individuals: "Excluded a different population from these surveys' than the one targeted.
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?"; 2) "During the past 3 months how often has your use of marijuana led to health, social, legal or financial problems?"; 3) "During the past 3 months how often have you found you could not do what was normally expected of you because of your use of marijuana?"; 4) "Was this concern [cannabis use] expressed in the past 3 months?", and 5) "Have you tried to do this [control, cut down or stop using marijuana] during the past 3 months?"
A binary variable was also derived for ranking individuals along risk levels for problematic cannabis consumption using the WHO ASSIST tool embedded in CTADS. The two categories were "Low risk for developing health and other problems" and "Moderate or high risk of developing health and other problems".
Survey weights were applied to all analyses to ensure that estimates were representative of the survey population and bootstrap weights were used in the modelling to produce confidence intervals and p-values that are appropriate for the complex survey design; a description of the bootstrap weighting and the Fay adjustment factor is available in the 2013 CTADS User Guide.