Method | Strengths | Weaknesses | No of studies* |
Smoker surveys | Buyers of smuggled tobacco have little or no legal incentive to conceal their behaviour (but analysis must still consider validity challenges listed under weaknesses); anonymity can be protected; direct method. | Relies on self-reported data which may presents validity problems in that respondents may under-report a behaviour viewed as socially unacceptable, may not know if product is licit or illicit or may not remember; previous studies have found smokers under-report tobacco consumption; representative sampling requires specific expertise; expensive and time consuming. | 15 |
Residual methods | Useful in countries with reliable and consistent estimates of tobacco consumption and sales over time; relies on well documented information; provable and reproducible; relatively inexpensive; useful in detecting deviations from the trend. | Relies on assumptions about tax paid sales and consumption estimates; reliant on quality and availability of survey data; comparisons may not consider tourists or migrants who are purchasing tobacco or roll your own tobacco products; cannot distinguish between tax avoidance and tax evasion; results may reflect temporal bias in tax-based sales. | 10 |
Butt collections | Simple and direct method; unobtrusive; avoids challenges of self-reported bias; similar collections over time may provide indications of trends in illicit consumption. | Difficult to achieve a representative sample as contraband consumption may vary widely by population, location and time of collection; is challenging to accurately distinguishing legal from illegal butts; cannot distinguish between legal tax avoidance and illegal tax evasion. | 3 |
Pack swap surveys | Relies on objective observational data (as opposed to self-reported data); similar surveys conducted over time may gauge trends. | May be challenging, expensive and/or time consuming to achieve a representative sample; distinguishing between legal tax avoidance (such as duty-free purchases) and illegal tax evasion requires additional data (information from smokers or lab inspection) and specific expertise; respondents with more than one pack may swap legal pack, resulting in low estimates. | 3 |
Developed from Merriman,27 Reuter and Majmundat,28 Ross3 and Stratton et al.47
*Some studies used multiple methods.
ITTP, illicit trade in tobacco products.