Table 2.

Eligibility criteria using SPIDER format

Criterion	Definition
(S) Sample	• Secondary school students (age 11–18), school staff, parents or other education professionals • Focused on whole population or students of a low socioeconomic status • Papers published from 1997 onwards, using data from 1997 onwards • Papers with abstracts written in English
(PI) Phenomenon of interest	• Friendship groups and peers
(D) Study design	• Qualitative • Mixed method with a qualitative element
(E) Evaluation outcomes	• Perceptions of the link between friendship, peers and smoking • Perceptions of smoking
(R) Research type	• Qualitative