Economic and econometric methods to measure the illicit tobacco trade: A scoping review.

This scoping review aimed to identify suitable economic and econometric methods for measuring the illicit tobacco trade. We searched six key databases for public health and economics papers (PubMed, CINAHL, EMBASE, EconLit, ABI/Inform, and Medline), two economic working paper platforms (SSRN and IDEAS), and grey literature via Google and expert-identified articles. Initial screening was undertaken by all authors, with at least three authors conducting a second screening and final paper selection. We included English-language papers (published from 2010 to July 2023) that applied economic or econometric models to illicit tobacco or related topics. We examined the methods, assessing their strengths and limitations from a health equity perspective, and evaluated their applicability to priority populations (rather than assessing the quality of individual models). The review included 39 studies: 16 applied consumption gap analysis (CGA), and 23 used other economic or econometric models (i.e., Exponentiated, Discrete Choice, Extended Cost-Benefit Analysis and A Static Partial Equilibrium, Consumption, Risk Prediction, A Forward-looking Behavioural, Integrated Micro-Macro Demand, Endogenous Switching Regression, Multiple and Non-Linear Regression, Dynamic Projection, Demand-driven Analytical, Econometric Regressions and Modelling and Two-way Fixed Effects models). CGA was primarily used to estimate the size and trends of the illicit tobacco market, whereas other models assessed and quantified past, existing, or potential behaviours related to engagement with tobacco and other products, including illicit tobacco. Only six of the 39 studies addressed health equity. Measuring the illicit tobacco trade is challenging due to its covert nature, methodological limitations, and scarce high-quality data. Method selection depends on the research objective: CGA is suitable for assessing national market trends but is limited in evaluating subpopulations or future policy impacts. Other non-CGA-based economic and econometric models are better for analysing or predicting user behaviour, including from a health equity perspective. Implications for public health: Measuring the illicit tobacco trade is challenging. This review identified a wide variety of economic or econometric methods on this topic and highlighted the need for a greater equity focus when applying these methods. Triangulating findings across the various methods is important moving forward.