Outcome
| Type |
Measure |
Description |
Time frame |
Safety issue |
| Primary |
Recruitment |
The number of completed respondents to recruitment ads, number of respondents eligible at initial screening, and number of respondents who completed baseline. |
Baseline |
|
| Primary |
Retention |
The % of participants in each condition who complete the follow-up assessment. |
4-week follow-up |
|
| Primary |
Acceptability |
Number of participants who selected agree or strongly agree on 5-point Likert scale rating of how likely participants would be to recommend the intervention to a friend, and how likely they would be to participate again. |
4-week follow-up |
|
| Primary |
Participation |
The number of posts created by participants |
4-week follow-up |
|
| Primary |
Post Engagement |
The median number of likes, shares and retweets, and unique commenters each participant post received. |
4 weeks |
|
| Primary |
Desirability of Tanning |
Scale measuring participants' belief that a tan is attractive. Scale ranges from 0-12 with higher scores indicating higher levels of belief that a tan is attractive. |
Baseline |
|
| Primary |
Desirability of Tanning |
Scale measuring participants' belief that a tan is attractive. Scale ranges from 0-12 with higher scores indicating higher levels of belief that a tan is attractive. |
4-week follow-up |
|
| Primary |
Desirability of Tanning Alternatives |
Average score on items relating to tanning alternative desirability. Scale ranges from 1 to 5, with higher scores indicating more positive attitudes towards tanning alternatives. |
Baseline |
|
| Primary |
Desirability of Tanning Alternatives |
Average score on items relating to tanning alternative desirability. Scale ranges from 1 to 5, with higher scores indicating more positive attitudes towards tanning alternatives. |
4-week follow-up |
|
| Primary |
Persuasive Impact of Participant Messages |
The mean of participants ratings for how persuasive they found each post (other than those they created) on a scale of 0-100, with higher scores indicating more persuasive. |
4-week follow-up |
|
| Primary |
Contamination |
The number of participants who report they saw the opposite conditions Facebook or Twitter feeds. |
4-week follow-up |
|
| Secondary |
Outdoor Tanning Intentions |
Three items assessed intentions to tan even once, intentions to tan regularly in the next year, and intentions to quit on a 7-point scale (0=definitely will not, 6=definitely will). |
Baseline |
|
| Secondary |
Outdoor Tanning Intentions |
Three items assessed intentions to tan even once, intentions to tan regularly in the next year, and intentions to quit on a 7-point scale (0=definitely will not, 6=definitely will). |
4-week follow-up |
|
| Secondary |
Sun Exposure |
How many hours the participant spent outside per week between the hours of 10am and 4pm. |
Baseline |
|
| Secondary |
Sun Exposure |
How many hours the participant spent outside per week between 10am and 4pm |
4-week follow-up |
|
| Secondary |
Outdoor Tanning |
How many times in the last 4 weeks the participant went outside for the purpose of tanning in the sun. |
Baseline |
|
| Secondary |
Outdoor Tanning |
How many times in the last 4 weeks the participant went outside for the purpose of tanning in the sun. |
4-week follow-up |
|
| Secondary |
Sun Protection |
Number of participants who reported using sun protection (sunscreen, protective clothing) often or always in the past month |
Baseline |
|
| Secondary |
Sun Protection |
Number of participants who reported using sun protection (sunscreen, protective clothing) often or always in the past month |
4-week follow-up |
|
| Secondary |
Indoor Tanning Behavior |
Number of indoor tanning visits in the previous month |
Baseline |
|
| Secondary |
Indoor Tanning Behavior |
Number of indoor tanning visits in the previous month |
4 weeks |
|
| Secondary |
Sunburn |
Number of participants with 1 or more sunburns in the past month |
baseline |
|
| Secondary |
Sunburn |
Number of participants with 1 or more sunburns in the past month |
4 weeks |
|
| Secondary |
Outdoor Tanning Duration |
Median reported average number of minutes tanned per episode in the past 4 weeks, among participants who tanned in the past 4 weeks. |
4 weeks |
|
| Secondary |
Outdoor Tanning Duration |
Median reported average number of minutes tanned per episode in the past 4 weeks, among participants who tanned in the past 4 weeks. |
Baseline |
|