Table 1 Primary and Secondary Outcome Measures

Intention

4

1 (strongly disagree) to 7 (strongly agree)

"I am willing to perform sun-protective behaviours."; "I intend to perform sun-protective behaviours."; "I plan to perform sun-protective behaviours."; "It is likely that I will perform sun-protective behaviours."

Behaviour

3

1 (never) to 7 (always)

"Think about the past week. In general, how often did you perform sun-protective behaviour?" "Think about the past week, how often did you perform sun-protective behaviour on a school day?"; "Think about the past week, how often did you perform sun-protective behaviour on the weekend?"

Secondary outcome variables

Attitude

6

1 (pleasant) to

7 (unpleasant)

1 (good) to 7 (bad)

1 (wise to 7 (unwise)

1 (difficult) easy (7)

1 (nice) to 7 (awful)

1 (negative) to 7 (positive)

"Performing sun-protective behaviours every time I go in the sun for more than 10 minutes during the next week, would be..."

Subjective Norms

2

1 (strongly disagree) to 7 (strongly agree)

"Those people who are important to me would want me to perform sun-protective behaviours." and "Most people who are important to me would approve of me performing sun-protective behaviours."

Perceived Behavioural Control

4

1 (strongly disagree) to 7 (strongly agree)

"I have complete control over whether I perform sun-protective behaviours."; "It is mostly up to me whether I perform sun-protective behaviours."; "If I wanted to it would be easy for me to perform sun-protective behaviours."; "I am confident that I could perform sun-protective behaviours."

Group Norms

4

1 (strongly disagree) to 7 (strongly agree) 1 (none) to 7 (all)

"Most of my friends perform sun-protective behaviours." and "My friends think that performing sun-protective behaviours is a good thing to do."

"How many of your friends would think that performing sun-protective behaviours every time you are out in the sun for more than 10 minutes in the next week is a good thing to do?" and "How many of your friends would perform sun-protective behaviours every time they are out in the sun for more than 10 minutes during the next week?"

Image Norms

5

1 (strongly disagree) to 7 (strongly agree)

"Young celebrities and movie stars always seem to have a tan."; "I see more examples of models who have pale skin on TV and in magazines than I used to."; "I think that to be a successful movie star or TV star you should have a tan."; "It seems that society wants young people to have a tan."; "I can think of many young movie stars and TV stars who have pale skin."