P N Lee Statistics and Computing (United Kingdom)

Sensory and consumer researchers are often required to identify clusters of consumers based on product liking. A widespread, if informally held, belief is that many studies contain a group of consumers whose data differ from the product means in their assigned cluster. The implication could be less discrimination between samples within a cluster, leading to poorer decision-making. This research presents a variant of existing cluster analysis methods to potentially improve insights by excluding subjects with non-typical response behaviour. The approach is intuitive, easy to implement, and cluster algorithm agnostic. After removing non-discriminators (i.e., those who like all samples equally), the principle is to conduct cluster analysis and then calculate the correlation of each subject's liking ratings with the mean in their assigned cluster, setting a fixed “trim out” threshold for the correlation coefficient. Consumers with correlations below the threshold are classified as non-typical and excluded. After introducing cluster trimming in a case study, the method is applied to another 29 data sets representing category appraisal and product optimisation applications. On average, the cluster-trimming process resulted in around 1/3 of study participants being “trimmed out.” These consumers tended to discriminate less between samples than the participants who were retained following cluster trimming. While cluster trimming was found to add some value regarding product discrimination, this benefit was somewhat obscured by the reduction in cluster size. Exploring within-cluster heterogeneity, made possible by examining histograms of correlation coefficients (r-values), is recommended. Because the cluster trimming approach is correlational, it should not be used in product studies with too few samples ( n < 6). • A correlational approach for refinement of consumer segments based on liking. • Subjects are retained or trimmed out based on similarity with the cluster product means. • Improves cluster homogeneity but has little impact on sample discrimination. • Cluster trimming is easy to perform and does not bias mean liking ratings.

A research protocol is a document that outlines the proposed research idea and is submitted to funding agencies, institutions, or journals for approval. Writing a research protocol represents a challenge, particularly for early-career researchers. In this guide, we aim to provide detailed guidance with the key components and offer practical tips for crafting a research protocol in line with the various study designs. Specifically, the structure of a research protocol should contain the following items: (1) a title that is specific, catchy, and impressive within the word limitation; (2) an abstract that briefs the critical points of the study; (3) an introduction highlighting the study context from broad to narrow and defining the knowledge gap; (4) a justification underlining the significance of the proposed study; (5) Specific, Measurable, Attainable, Relevant, and Time-bound (SMART) objective(s) and aim(s); (6) a methodology covering seven sub-items, including [i] study design and settings, [ii] study subjects, [iii] sample size calculation and sampling, [iv] participants recruitment and follow-up, [v] questionnaire development, [vi] potential variables and outcomes, and [vii] data analysis plan; (7) dissemination of the results; (8) ethics and conflict of interests; (9) budgets analysis/ funding disclosure; and (10) references. This guide will give an overview of these steps and provide clear and concise tips on how to successfully draft a scientific protocol. With careful planning and appropriate guidance, it is possible to develop a well-structured and compelling protocol to obtain approval for the conduction of the study or funding from agencies, institutions, or organizations.

Summary Background We previously estimated the impact of introducing heat-not-burn products and e-cigarettes in Germany on smoking-related disease mortality in men and women aged 30–79 years between 1995 and 2015. Here, we estimate the impact by socioeconomic group. Methods Individuals with a defined baseline cigarette smoking distribution were followed under a “Null Scenario” (no reduced-risk products) and “Alternative Scenarios” (reduced-risk products introduced). Transition probabilities allowed estimation of annual product use changes, with individual product histories used to estimate reductions in deaths and life-years lost. Here, however, individuals were classified into two socioeconomic groups defined by income and education, with allowance for variation by group in initial smoking prevalence and the probability of changing product use, or of changing socioeconomic group. Results With no allowance for socioeconomic group, deaths would have reduced by 217,000 (from 852,000 for continued smoking) had everyone immediately ceased smoking in 1995 and by 40,000 to 179,000 had one or two types of reduced-risk products – the heat-not-burn product and the e-cigarette – been adopted by smokers to varying extents. With such allowance, we estimate substantial drops in each socioeconomic group. Where all cigarette smokers switched immediately, half of them to heat-not-burn products, half to e-cigarettes, the estimated drops in deaths were 60,000 in group A (higher socioeconomic group) and 122,000 in group B (lower), about 82% of the drops associated with immediate cessation (73,000 in A and 148,000 in B). With more gradual conversion, the drops were 26,648 in A and 53,000 in B, about 35% of those from cessation. The drops in deaths and life-years saved were about 2 and 1.5 times higher in group B, respectively, associated with its greater numbers, older age, and higher smoking prevalence. The estimated reductions would increase upon considering more diseases, a wider age range, or longer follow-up. Methodological limitations would not affect the conclusion that introducing these products in 1995 in Germany could have substantially reduced deaths and life-years lost in both groups, more so in B. Conclusions Although cessation is optimal for reducing mortality, switching to reduced-risk products also provides substantial health gains. A public health approach encouraging lower socioeconomic group smokers to switch to reduced-risk products could diminish smoking-related health inequalities relative to continued smoking.

Abstract Background Smoking is associated with cancer and cardiorespiratory disease mortality. Reducing smoking prevalence reduces deaths and life-years lost. Here, we estimate the impact of introducing heat-not-burn products and e-cigarettes in Germany from 1995 to 2015 on mortality from lung cancer, chronic obstructive pulmonary disease, ischaemic heart disease, and stroke in men and women aged 30–79 years. Methods We used the previously described population health impact model. Modelling starts with individuals of a given sex and age range with a defined cigarette smoking distribution. They are then followed under a “Null Scenario”, where reduced-risk products are never introduced, and one of seven “Alternative Scenarios”, where they are. Transition probabilities allow tobacco product use to change annually, and the individual product histories then allow estimation of risks, relative to never users, for each year and Scenario, which are then used to estimate reductions in deaths and life-years lost for each Alternative Scenario. Results In the Null Scenario, we estimated 852,357 deaths from cigarette smoking, with 8.61 million life-years lost. Had everyone quit in 1995, with no further use of the three products, these numbers would reduce by 216,650 and 2.88 million. The reductions would be 159,278 and 2.06 million with an immediate complete switch from cigarettes to heat-not-burn products, and 179,470 and 2.34 million with an immediate switch to 50% heat-not-burn products and 50% e-cigarettes. In four Scenarios with a more gradual switch, estimated decreases were 39,818–81,293 deaths and 0.50–1.05 million life-years, representing 17.5%-37.5% of the effect of cessation. These estimates assume switching to heat-not-burn products and e-cigarettes involves risk decreases of 80% and 95% of those from quitting. The decreases would have increased, had more diseases and a wider age range been considered, and also with a longer follow-up period, the decreases increasing markedly with time. Conclusions Various limitations are discussed, none affecting our conclusion that introducing these new products into Germany in 1995 could have substantially reduced mortality. Our results imply deaths from cigarette smoking could be substantially reduced, both by cessation and switching to reduced-risk products. Risk-proportionate public health campaigns and regulation might increase such switching.

Background: Compared to cigarette smoking, e-cigarette use is likely to present a reduced risk of smoking-related disease (SRD). However, several studies have shown that vaping predicts smoking initiation and might provide a gateway into smoking for those who otherwise would never have smoked. This paper considers various aspects of the gateway issue in youths. Methods: Here, we reviewed studies (N=15) of the gateway effect examining how extensively they accounted for confounders associated with smoking initiation in youths. We estimated how omitting a confounder, or misclassifying it, might bias the association between vaping and smoking initiation. We assessed how smoking prevalence might be affected by any true gateway effect, and examined trends in youth smoking and e-cigarette use from national surveys. Results:The list of smoking predictors adjusted for in studies reporting a significant gateway effect is not comprehensive, rarely considering internalising/externalising disorders, outcome expectancies, school performance, anxiety, parental smoking and peer attitudes. Furthermore, no study adjusted for residual confounding from inaccurately measured predictors. Better adjustment may substantially reduce the estimated gateway effect. Calculations showed that as any true gateway effects increase, there are much smaller increases in smoking prevalence, and that gateway effects increase only if initiating vaping is more frequent than initiating smoking. These effects on prevalence also depend on the relative odds of quitting vs. initiation. Data from five surveys in US/UK youths all show that, regardless of sex and age, smoking prevalence in 2014-2016 declined faster than predicted by the preceding trend, suggesting the absence of a substantial gateway effect. We also present arguments suggesting that even with some true gateway effect, introducing e-cigarettes likely reduces SRD risk. Conclusions: A true gateway effect in youths has not yet been demonstrated. Even if it were, e-cigarette introduction may well have had a beneficial population health impact.