Table 1.

Schedule of assessments and measures.

Measure	Baseline (T1, week 1)	Intervention (weeks 2-9)	Postintervention (T2, week 9)	Follow-up (T3, week 13)
Purpose designed #chatsafe online safety questionnaire	✓	N/Aa	✓	✓
Patterns of Social Media Use Questionnaire (including 12 items to assess social media usage for the purposes of communicating about suicide and-self harm specifically)	✓	N/A	✓	✓
Perceived Internet-Self Efficacy Scale	✓	N/A	✓	✓
Willingness to Intervene Against Suicide Questionnaire	✓	N/A	✓	✓
Patient Health Questionnaire-9	✓	N/A	✓	✓
Purpose designed 7-items assessing exposure to, and personal experiences of, suicide and self-harm	✓	N/A	✓	✓
Purpose designed 9-item Weekly Evaluation and Engagement survey	N/A	✓	N/A	N/A
Purpose designed 1-item assessing participant reasons for withdrawal/noncomplete	✓	✓	✓	✓
Purpose designed 10-items assessing participants’ evaluations of the intervention content immediately postintervention	N/A	N/A	✓	N/A
Sexual Health Capacity Scale	✓	N/A	✓	✓
Self-Efficacy Protective Sexual Behaviours Scale	✓	N/A	✓	✓
Sexual Health Questionnaire	✓	N/A	✓	✓

^aN/A: not applicable.