Design
Data came from Wave 7 of the Youth Tobacco Policy Survey (YTPS), a long-running, repeat cross-sectional study examining the impact of tobacco policies on adolescents. FACTS international, a market research company, recruited participants and conducted the fieldwork in August and September 2014. Parental and participant informed consent was obtained prior to each interview. The survey comprised an in-home face-to-face interview, followed by a self-completion questionnaire to gather more sensitive information. To maximise privacy, should anyone else be present where the interview was taking place, questions were displayed on showcards to enable participants to read responses from the card and give the number corresponding to their answer. Ethical approval was obtained from the Stirling Management School ethics committee.
Sampling strategy
Using random location quota sampling, a sample of 11–16 year olds was drawn from households across the UK. Sampling involved random selection of 92 electoral wards stratified by Government Office Region and A Classification Of Residential Neighbourhoods (ACORN) classification (a geodemographic classification system that describes demographic and lifestyle profiles of small geographic areas) to ensure coverage of a range of geographic areas and socio-demographic backgrounds. Wards covering the islands, areas north of the Caledonian Canal, or those with fewer than three urban/suburban Enumeration Districts were excluded from the sampling frame for cost and practicality reasons. In each selected ward interviewers approach households until a quota of 15 interviews is obtained, balanced across gender and age. A total sample of 1205 was achieved. Comparative census data for England and Wales indicate that the sample was in line with national figures for gender and age (ONS 2012) and also in line with smoking prevalence among 11–15 year olds in England (Fuller 2015).
Development of the survey items and testing
Research between April and July 2014 informed the development and refinement of the e-cigarette measures. Initially, six focus groups were conducted with 11–16 year olds to explore their knowledge of e-cigarettes, how they think about and respond to them, and the language and meanings they attach to them. A draft questionnaire was developed from the emerging themes using, as far as possible, the terms the young people used. This was piloted with 11 participants aged 11–16 years. Two professional market research interviewers were involved in administering the pilot questionnaire. Each interview was observed by a member of the research team, to test the flow of the questionnaire, timing, and comprehension of questions and visual stimuli. On completion of the questionnaire, the interviewer left the room and the researcher conducted an in-depth cognitive interview to assess participant understanding of the measures, relevance of questions and ability to respond.
Measures
General information
Information was obtained on age and gender. Social grade was based on the UK demographic classifications system derived from the National Readership Survey and determined by the occupation of the chief income earner in the household. Never smokers were categorised as those who had ‘never tried smoking, not even a puff or two’. Ever smokers included those who indicated being regular smokers (at least one cigarette a week), occasional smokers (less than one a week), those who used to smoke and those who had tried smoking only once.
Awareness of e-cigarettes
Questions on e-cigarettes were introduced with: ‘Now we’d like you to think about electronic cigarettes, sometimes called e-cigarettes or e-shisha. E-cigarettes puff a vapour that looks like smoke but, unlike normal cigarettes, you don’t light them with a flame and they don’t burn tobacco. Have you ever heard of e-cigarettes?’
Subsequent questions on e-cigarettes were asked of all respondents, regardless of whether they had heard of e-cigarettes, by including a description and visual representation of e-cigarettes: ‘E-cigarettes come in different styles. Some look similar to normal cigarettes and have a glowing tip while some look more like pens. Here is a picture of some different styles of e-cigarettes (see Fig. 1). Have you ever seen any of these types of e-cigarettes?’
E-cigarette use
One item assessed e-cigarette use: ‘Which of these best describes whether or not you have ever used or tried e-cigarettes?’ Response options were ‘I have never used e-cigarettes’, ‘I have only ever tried e-cigarettes once or twice’, ‘I have used e-cigarettes in the past, but I never use them now’, ‘I occasionally use e-cigarettes (less than once a month)’, ‘I use e-cigarettes at least once a month’, and ‘I use e-cigarettes at least once a week’.
Awareness of e-cigarette promotion
Awareness of e-cigarette promotion was assessed via nine items and included TV, radio, newspapers/magazines, posters/billboards, point-of-sale display, social media, sports/games sponsorship, special price offers, and famous people pictured with e-cigarettes. For each type of promotion, participants were presented with a showcard and asked; ‘For each one can you tell me if you have seen anything like this in the last month?’ with response options of ‘Yes’, ‘No’, ‘Don’t know’.
E-cigarette brand awareness
Brand awareness was assessed via three items. Brand recall was assessed by asking participants to name brands of e-cigarettes that they had heard of. No prompts were given and a maximum of six brands were recorded. Brand identification was assessed by showing a visual prompt with three brands of e-cigarettes with the brand name masked out (Fig. 2a) and asking them to name each brand. Brand recognition was assessed by showing a visual of the same three brands, but without the brand name masked out, and asking if they had seen each before (Yes/No/Not sure) (Fig. 2b).
E-cigarette flavour awareness
Participants were asked: ‘Do you think that e-cigarettes all taste the same or do you think they come in different flavours?’ with response options ‘They come in different flavours’, ‘All taste the same’ and ‘Don’t know’. Those who answered ‘They come in different flavours’ were then asked: ‘Can you tell me any different flavours that you’ve heard of for e-cigarettes’, with a maximum of six flavours recorded.
Perceptions of product harm
To provide a general measure of perception of harm, participants were asked ‘Tell me, overall, what you think about people using e-cigarettes’. Participants were then asked to rate how harmful, if at all, four different flavours (tobacco, cherry, candy floss, coffee) would be to the health of the person using it. Responses for all items were provided on a five-point sematic scale ranging from ‘Not at all harmful to health (1)’ to ‘Very harmful to health (5)’.
Perceived user image for e-cigarette flavours
Participants were asked to rate how likely or unlikely it would be for ‘an adult who is trying to give up smoking’ to use or try e-cigarettes with different flavours (tobacco, cherry, candy floss and coffee). The same question was also asked for ‘someone their age who has never smoked’. Responses ranged from ‘Very likely (1)’ to ‘Very unlikely (5)’.
Statistical analysis
Data were analysed using SPSS (version 21). Descriptive data are weighted for age and gender. Paired t-tests were run, on weighted data, to produce mean scores for the following items: (1) perception of harm from a particular flavour of e-cigarettes; (2) perceived likelihood of a particular flavour being used by an adult smoker who is trying to give up (3) perceived likelihood of a particular flavour being tried by someone their age who has never smoked and (4) perceived likelihood of a particular flavour being used by an adult smoker (trying to give up) relative to the perceived likelihood of that same flavour being tried by a never smoker of their age.
As data from all the five-point scales are ordinal, the analysis used non-parametric approaches, initially using the Friedman Test to examine whether responses differed depending on the flavour asked about. Where the Friedman Test detected differences, post hoc tests were conducted using the Wilcoxon signed rank test, a non-parametric procedure suited to paired data. When examining perception of harm from a particular flavour, each flavour was compared against the general measure of harm from e-cigarettes. When examining likelihood of different types of people using each e-cigarette flavour, the tobacco flavour was used as the reference category and compared with each of the other three flavours (cherry, candy floss and coffee). To account for multiple comparisons, a Bonferroni Correction was applied to the critical p value, resulting in a p value <0.0125 being required for results to reach significance. All descriptive data, including the paired means, are based on weighted data. All non-parametric tests were run on unweighted data. Significance levels quoted are from unweighted non-parametric tests.