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Table 3 TPB questionnaire items and alpha reliabilities

From: Employing the theory of planned behaviour to design an e-cigarette education resource for use in secondary schools

Construct Number of items Sample items
Intention 3 I intend (want to/going to) use an e-cigarette within the next month; (5) strongly agree (1) strongly disagree (Cronbach’s α = 0.97).
Attitude 4 Direct attitude:
For me, using an e-cigarette within the next month would be very healthy (5)/very unhealthy (1); very good (5)/very bad (1); very foolish (1)/ very wise (5). (Cronbach’s α = 0.89).
8 Indirect ‘belief-based’ attitude:
Seven outcome evaluations (See Table 2), e.g. ‘safer alternative to cigarettes’: very good (+ 2) to very bad (− 2) multiplied by the corresponding behavioural belief, e.g. ‘using an e-cigarette would be a safer alternative to cigarettes’: very true (5) to very untrue (1).
Subjective Norm 4 Direct subjective norm:
Most people who are important to me think that I should (would approve/would want me to) use an e-cigarette: ‘strongly agree’ (5) to strongly disagree (1). (Cronbach’s α = 0.67).
6 Indirect subjective norm:
Six normative beliefs (See Table 2) e.g. ‘my parents think that I should use an e-cigarette’: strongly agree (+ 2) to strongly disagree (− 2) multiplied by the corresponding motivation to comply e.g. ‘generally speaking I want to do what my parents want me to do’: strongly agree (5) to strongly disagree (1).
Perceived Behavioural Control 3 Direct perceived behavioural control:
Whether I use an e-cigarette or not is entirely up to me: strongly agree (5) to strongly disagree (1); It is mostly up to me whether I use an e-cigarette or not: strongly agree (5) to strongly disagree (1); It is my decision whether I use an e-cigarette or not: strongly agree (5) to strongly disagree (1). (Cronbach’s α = 0.82).
11 Indirect perceived behavioural control:
Eleven control beliefs (See Table 2) e.g. The curiosity of trying an e-cigarette would encourage me to use an e-cigarette: very true (5) to very untrue (1)/ Adhering to the law would prevent me from using an e-cigarette: very true (1) to very untrue (5).
Self-efficacy 3 Direct self-efficacy
I am confident that I could/I am sure that I could/It is easy for me to use an e-cigarette: strongly agree (5) to strongly disagree (1). (Cronbach’s α = 0.89).
Knowledge of e-cigarettes 7 The legal age to purchase an e-cigarette is 18 years/ E-cigarettes do not contain nicotine/E-cigarettes do not produce tar and carbon monoxide: True/False
E-cigarettes use 16 Do you/your mother/your father/your care giver use/ever used e-cigarettes Yes/No
How often do you/did you use e-cigarettes (Occasionally, but not every day/1–2 times per week/3–4 times per week/Only on days that I am/was at school/everyday/weekends only)
Advertising/Exposure to e-cigarettes 3 Where did you first hear about or see e-cigarettes? Where have you seen e-cigarettes advertised? Have you been taught about e-cigarettes in school?
Smoking 4 Do you/your mother/father/care giver smoke tobacco cigarette: Yes/No
How often do you smoke: Everyday/1–2 times per week/3–4 times per week/only the days I am at school/weekends only