Table 2 Summary of progression criteria to guide decision about whether to proceed to full-scale evaluation, sources of evidence for each criterion and whether targets were met

In at least 4 schools, 60% of nominated students recruited and complete the training.

50%, in at least 4 schools

Amber target achieved in fewer than 4 schools

Source 8; attendance at recruitment meeting

Red

In ≥4 schools, 60% of PS complete training, send 3+ messages/have 3+ conversations and attend 2+ follow-up meetings

50%, in ≥4 schools

As above

Source 5; source 8

Green

In ≥4 schools, 60% of PS report that they ‘liked’ the role

45%, in ≥4 schools.

As above

Source 5: ‘I liked being a peer supporter’ (5 point likert scale)

Green

In at least 4 schools, 60% of students who are exposed to STASH agree that the intervention was acceptable.

50%, in ≥4 schools.

As above

Source 2: ‘The way the STASH project was run/The information given in STASH was acceptable’ (2 items; 5-point likert scale)

Green

No major acceptability issues raised^^^

1–2 major issues

Major acceptability issues

Source 6:Teachers

Green

Less than 15% of PS report their parents/carers unhappy about them being a PS

<20%

Amber target not met

Source 5; Source 6

Green

In at least 4 schools, student response rates of >70% at baseline and follow-up (FU)

Response of >60 in ≥4 schools

Amber target not met

Source 1,2,3 (Control, baseline and follow-up questionnaires); Source 6 (PS and non-PS interviews)

Green