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AbstractIn the quest to model various phenomena, the foundational importance of parameter identifiability to sound statistical modeling may be less well appreciated than goodness of fit. Identifiability concerns the quality of objective information in data to facilitate estimation of a parameter, while nonidentifiability means there are parameters in a model about which the data provide little or no information. In purely empirical models where parsimonious good fit is the chief concern, nonidentifiability (or parameter redundancy) implies overparameterization of the model. In contrast, nonidentifiability implies underinformativeness of available data in mechanistically derived models where parameters are interpreted as having strong practical meaning. This study explores illustrative examples of structural nonidentifiability and its implications using mechanistically derived models (for repeated presence/absence analyses and dose–response of Escherichia coli O157:H7 and norovirus) drawn from quantitative microbial risk assessment. Following algebraic proof of nonidentifiability in these examples, profile likelihood analysis and Bayesian Markov Chain Monte Carlo with uniform priors are illustrated as tools to help detect model parameters that are not strongly identifiable. It is shown that identifiability should be considered during experimental design and ethics approval to ensure generated data can yield strong objective information about all mechanistic parameters of interest. When Bayesian methods are applied to a nonidentifiable model, the subjective prior effectively fabricates information about any parameters about which the data carry no objective information. Finally, structural nonidentifiability can lead to spurious models that fit data well but can yield severely flawed inferences and predictions when they are interpreted or used inappropriately.

Backround: The availability of contraband cigarettes provides incentives for price-sensitive smokers to reduce their monetary costs of smoking. The objectives of this study were to examine whether Canadian smokers' geographic proximity to First Nations reserves and attempts to quit smoking influenced the likelihood of purchasing lower-cost cigarettes from reserves. Methods: Data were from the International Tobacco Control (ITC) Canada Survey, a prospective survey of Canadian adult smokers conducted from 2002 to 2014 using telephone and online interviewing methods. Analysis was restricted to smokers from Ontario (n=2105) and Quebec (n=1427) participating in at least one survey wave. Smokers' postal codes were used to calculate distance to the nearest reserve. Weighted logistic generalised estimating equations (GEE) regression examined the linear relationship between distance and the log odds of last purchasing cigarettes on reserve in each province. GEE models also examined the relationship between past-year quit attempts and the log odds of on-reserve purchasing. Results: Controlling for other factors, from 2002–2014, smokers from Ontario who lived 10 km closer to reserves than otherwise similar smokers had significantly higher odds of last purchasing on reserve (OR ranged from 1.16 to 1.65). Distance had little effect on smokers' purchasing behaviours in Quebec. Moreover, in Ontario, for every 10 km increase in distance, smokers who did not try to quit had significantly greater odds of purchasing from a reserve than smokers who tried to quit (p=0.002). Conclusion: In order for tobacco taxation policies to achieve their maximal benefit, governments must limit potential sources of lower-cost cigarettes. Collaborative governance arrangements can ensure tobacco products sold on reserve to non-Indigenous people are appropriately taxed while allowing First Nations communities to keep the revenue generated by such taxes. ; US National Cancer Institute || Canadian Institutes of Health Research || Canadian Tobacco ...

INTRODUCTION: The rapid rise in electronic cigarettes (ECs) globally has stimulated much debate about the relative risk and public health impact of this new emerging product category as compared to conventional cigarettes. The sale and marketing of ECs containing nicotine are banned in many countries (eg, Australia) but are allowed in others (eg, United Kingdom). This study examined prevalence and correlates of the belief that ECs are a lot less harmful than conventional cigarettes under the different regulatory environments in Australia (ie, more restrictive) and the United Kingdom (ie, less restrictive). METHODS: Australian and UK data from the 2013 survey of the International Tobacco Control Four-Country project were analyzed. RESULTS: More UK than Australian respondents (58.5% vs. 35.2%) believed that ECs are a lot less harmful than conventional cigarettes but more respondents in Australia than in the United Kingdom selected "Don't Know" (36.5% vs. 17.1%). The proportion that responded "A little less, equally or more harmful" did not differ between countries. Correlates of the belief that ECs are "A lot less harmful" differed between countries, while correlates of "Don't Know" response did not differ. CONCLUSIONS: Consistent with the less restrictive regulatory environment affecting the sale and marketing of ECs, smokers and recent ex-smokers in the United Kingdom were more likely to believe ECs were less harmful relative to conventional cigarettes compared to those in Australia. IMPLICATIONS: What this study adds: Among smokers and ex-smokers, this study found that the belief that ECs are (a lot) less harmful than conventional cigarettes was considerably higher in the United Kingdom than in Australia in 2013. The finding is consistent with the less restrictive regulatory environment for ECs in the United Kingdom, suggesting that the regulatory framework for ECs adopted by a country can affect smokers' perceptions about the relative harmfulness of ECs, the group that stands to gain the most from having an accurate belief about the relative harms of ECs.

Les enquêtes recourant à un mode mixte de collecte sont de plus en plus nombreuses, et il devient nécessaire de tester les écarts entre les réponses obtenues par téléphone et par internet. Cet article analyse les effets des différents modes de collecte en utilisant la vague 1 de l'enquête International Tobacco Control (ITC) des Pays-Bas réalisée par internet (CAWI) et par téléphone (CATI). Pour de nombreuses questions, les échantillons présentent des distributions de réponse différentes. C'est dû en partie à des effets de sélection, car les répondants sont recrutés par des procédures différentes et les échantillons n'ont pas les mêmes caractéristiques démographiques, et en partie à des facteurs d'administration des questions, les répondants traitant différemment les items de réponse en fonction du mode de collecte. L'objectif est ici de présenter une modélisation qui prend en compte à la fois les effets de sélection et d'administration dans une enquête utilisant un mode mixte de collecte. Le modèle est aussi intégré dans une analyse des réactions à des mentions figurant sur les paquets de cigarettes, d'après les enquêtes ITC aux Pays-Bas, en Allemagne, en France et au Royaume-Uni.

INTRODUCTION: E-cigarettes (ECs) have gained significant attention in recent years. They have been introduced in jurisdictions with divergent existing laws that affect their legality. This provides the opportunity for natural experiments to assess effects of such laws in some cases independent of any formulated government policy. We compare patterns of EC awareness and use over a 3 year period in Australia where laws severely restrict EC availability, with awareness and use in the United Kingdom where ECs are readily available. METHODS: Data analyzed come from Waves 8 and 9 (collected in 2010 and 2013, respectively) of the International Tobacco Control surveys in Australia and the United Kingdom (approximately 1,500 respondents per wave per country). RESULTS: Across both waves, EC awareness, trial, and use among current and former smokers were significantly greater in the United Kingdom than in Australia, but all 3 of these measures increased significantly between 2010 and 2013 in both countries, and the rate of increase was equivalent between countries. Seventy-three percent of U.K. respondents reported that their current brands contained nicotine as did 43% in Australia even though sale, possession and/or use of nicotine-containing ECs without a permit are illegal in Australia. EC use was greater among smokers in both countries, at least in part due to less uptake by ex-smokers. CONCLUSIONS: EC awareness and use have risen rapidly between 2010 and 2013 among current and former smokers in both Australia and the United Kingdom despite different EC regulatory environments. Substantial numbers in both countries are using ECs that contain nicotine.

This study aims to test the pathways of change from individual exposure to smoke-free legislation on smoking cessation, as hypothesized in the International Tobacco Control (ITC) Conceptual Model. A nationally representative sample of Dutch smokers aged 15 years and older was surveyed during 4 consecutive annual surveys. Of the 1,820 baseline smokers, 1,012 participated in the fourth survey. Structural Equation Modeling was employed to test a model of the effects of individual exposure to smoke-free legislation through policy-specific variables (support for smoke-free legislation and awareness of the harm of [secondhand] smoking) and psychosocial mediators (attitudes, subjective norm, self-efficacy, and intention to quit) on quit attempts and quit success. The effect of individual exposure to smoke-free legislation on smoking cessation was mediated by 1 pathway via support for smoke-free legislation, attitudes about quitting, and intention to quit smoking. Exposure to smoke-free legislation also influenced awareness of the harm of (secondhand) smoking, which in turn influenced the subjective norm about quitting. However, only attitudes about quitting were significantly associated with intention to quit smoking, whereas subjective norm and self-efficacy for quitting were not. Intention to quit predicted quit attempts and quit success, and self-efficacy for quitting predicted quit success. Our findings support the ITC Conceptual Model, which hypothesized that policies influence smoking cessation through policy-specific variables and psychosocial mediators. Smoke-free legislation may increase smoking cessation, provided that it succeeds in influencing support for the legislation.

BACKGROUND: This study presents perceptions of the harmfulness of electronic cigarettes (e-cigarettes) relative to combustible cigarettes among smokers from six European Union (EU) countries, prior to the implementation of the EU Tobacco Products Directive (TPD), and 2 years post-TPD. METHODS: Data were drawn from the EUREST-PLUS ITC Europe Surveys, a cohort study of adult smokers (≥18 years) from Germany, Greece, Hungary, Poland, Romania and Spain. Data were collected in 2016 (pre-TPD: N = 6011) and 2018 (post-TPD: N = 6027). Weighted generalized estimating equations were used to estimate perceptions of the harmfulness of e-cigarettes compared to combustible cigarettes (less harmful, equally harmful, more harmful or 'don't know'). RESULTS: In 2016, among respondents who were aware of e-cigarettes (72.2%), 28.6% reported that they perceived e-cigarettes to be less harmful than cigarettes (range 22.0% in Spain to 34.1% in Hungary). In 2018, 72.2% of respondents were aware of e-cigarettes, of whom 28.4% reported perceiving that e-cigarettes are less harmful. The majority of respondents perceived e-cigarettes to be equally or more harmful than cigarettes in both 2016 (58.5%) and 2018 (61.8%, P > 0.05). Overall, there were no significant changes in the perceptions that e-cigarettes are less, equally or more harmful than cigarettes, but 'don't know' responses significantly decreased from 12.9% to 9.8% (P = 0.036). The only significant change within countries was a decrease in 'don't know' responses in Spain (19.3–9.4%, P = .001). CONCLUSIONS: The majority of respondents in these six EU countries perceived e-cigarettes to be equally or more harmful than combustible cigarettes.

Background This study presents perceptions of the harmfulness of electronic cigarettes (e-cigarettes) relative to combustible cigarettes among smokers from six European Union (EU) countries, prior to the implementation of the EU Tobacco Products Directive (TPD), and 2 years post-TPD. Methods Data were drawn from the EUREST-PLUS ITC Europe Surveys, a cohort study of adult smokers (≥18 years) from Germany, Greece, Hungary, Poland, Romania and Spain. Data were collected in 2016 (pre-TPD: N = 6011) and 2018 (post-TPD: N = 6027). Weighted generalized estimating equations were used to estimate perceptions of the harmfulness of e-cigarettes compared to combustible cigarettes (less harmful, equally harmful, more harmful or 'don't know'). Results In 2016, among respondents who were aware of e-cigarettes (72.2%), 28.6% reported that they perceived e-cigarettes to be less harmful than cigarettes (range 22.0% in Spain to 34.1% in Hungary). In 2018, 72.2% of respondents were aware of e-cigarettes, of whom 28.4% reported perceiving that e-cigarettes are less harmful. The majority of respondents perceived e-cigarettes to be equally or more harmful than cigarettes in both 2016 (58.5%) and 2018 (61.8%, P > 0.05). Overall, there were no significant changes in the perceptions that e-cigarettes are less, equally or more harmful than cigarettes, but 'don't know' responses significantly decreased from 12.9% to 9.8% (P = 0.036). The only significant change within countries was a decrease in 'don't know' responses in Spain (19.3–9.4%, P = .001). Conclusions The majority of respondents in these six EU countries perceived e-cigarettes to be equally or more harmful than combustible cigarettes.

Background: This study presents perceptions of the harmfulness of electronic cigarettes (e-cigarettes) relative to combustible cigarettes among smokers from six European Union (EU) countries, prior to the implementation of the EU Tobacco Products Directive (TPD), and 2 years post-TPD. Methods: Data were drawn from the EUREST-PLUS ITC Europe Surveys, a cohort study of adult smokers (>= 18 years) from Germany, Greece, Hungary, Poland, Romania and Spain. Data were collected in 2016 (pre-TPD: N = 6011) and 2018 (post-TPD: N = 6027). Weighted generalized estimating equations were used to estimate perceptions of the harmfulness of e-cigarettes compared to combustible cigarettes (less harmful, equally harmful, more harmful or 'don't know'). Results: In 2016, among respondents who were aware of e-cigarettes (72.2%), 28.6% reported that they perceived e-cigarettes to be less harmful than cigarettes (range 22.0% in Spain to 34.1% in Hungary). In 2018, 72.2% of respondents were aware of e-cigarettes, of whom 28.4% reported perceiving that e-cigarettes are less harmful. The majority of respondents perceived e-cigarettes to be equally or more harmful than cigarettes in both 2016 (58.5%) and 2018 (61.8%, P>0.05). Overall, there were no significant changes in the perceptions that e-cigarettes are less, equally or more harmful than cigarettes, but 'don't know' responses significantly decreased from 12.9% to 9.8% (P = 0.036). The only significant change within countries was a decrease in 'don't know' responses in Spain (19.3-9.4%, P = .001). Conclusions: The majority of respondents in these six EU countries perceived e-cigarettes to be equally or more harmful than combustible cigarettes.

Population-level interventions represent the only real approach for combatting the tobacco epidemic. There is thus great importance in conducting rigorous evaluation studies of tobacco control policies and regulations such as those arising from the WHO Framework Convention on Tobacco Control (FCTC) and the European Union's 2014 Tobacco Products Directive (TPD). The ITC 6 European Countries Survey, a component of the Horizon 2020 Project entitled European Regulatory Science on Tobacco: Policy Implementation to Reduce Lung Disease (EUREST-PLUS), was created to evaluate and impact of the TPD in six EU Member States: Germany, Greece, Hungary, Poland, Romania, and Spain. In each country, a cohort survey of a representative national sample of 1000 smokers was conducted. This paper describes the conceptual model, methodology, and initial survey statistics of Wave 1 of the ITC 6E Survey, which was conducted June–September 2016. The ITC 6E Survey's conceptual model, methodology, and survey instrument, were based on the broader 29-country ITC Project cohort studies, which have been conducted since 2002. The commonality of methods and measures allow a strong potential for cross-country comparisons between the 6 EU countries of the ITC 6E Project and 3 other EU countries (England, France, The Netherlands) in the ITC Project, as well as the broader set of ITC countries outside the EU.