Table 2.

Primary and secondary outcome measures.

Construct and Measure	Response Options	Data Collection Occasions	Items
Primary Outcome Measure
Positive bystander intervention behaviours for violence prevention [36]	•I didn't say anything (−1) •I told the person in public that acting like that was not okay (+1) •I laughed or went along with it (−1) •I told the person in private that acting like that was not okay (+1) •I talked to an important adult about it privately (like a youth leader, teacher, coach) (+1) •I have not experienced this in the past 3 months (0) -Analyzed by creating sum score	T1 T2 T3	The following questions ask about specific behaviors that you may have seen or heard among your male peers or friends. If you experienced this at least once in the past 3 months, how did you respond? 1.Making rude or disrespectful comments about a girl's body, clothing, or make-up. 2.Spreading rumors about a girl's sexual reputation, like saying “she's easy.” 3.Telling sexual jokes that disrespect women and girls. 4.Bragging about what they and their girlfriend do sexually. 5.Showing other people sexual messages or naked/sexual pictures of a girl on a cell phone or the internet. 6.Doing unwelcome or uninvited things toward a girl (or group of girls) such as howling, whistling, or making sexual gestures. 7.Fighting with a girl where he's starting to cuss at or threaten her. 8.Taking sexual advantage of a girl (like touching, kissing, having sex with) who is drunk, high from drugs, or passed out. 9.Shoving, grabbing, or otherwise physically hurting a girl.
Secondary Outcome Measures
Adolescent dating violence perpetration: Conflict in Adolescent Dating Relationships Inventory (CADRI) [41]/Electronic Intrusiveness items [42]	Inclusion question: Have you ever had a dating relationship? A dating relationship is defined as the kind of relationship where you like a person, they like you back, and other people know that you are together. This does not have to mean going on a formal date. [43],p268 Yes No (skip out) Not sure – Response options: ‘never’, ‘once’, and ‘more than once’; dichotomized as any endorsement	T1 T3	Have you done any of the following to a dating partner in the past 6 months? Don't count it if you did it in self-defense. 1.I threw something at them 2.I kicked, hit or punched them 3.I slapped them or pulled their hair 4.I pushed, shoved or shook them 5.I destroyed or threatened to destroy something they valued 6.I deliberately tried to frighten them 7.I threatened to hurt them 8.I threatened to hit them or throw something at them 9.I touched them sexually when they didn't want me to 10.I forced them to have sex when they didn't want to 11.I threatened them in an attempt to have sex with them 12.I kissed them when they didn't want me to 13.I tried to turn their friends against them 14.I said things to their friends about them to turn their friends against them 15.I spread rumors about them 16.I did something to try to make them jealous 17.I brought up something bad they had done in the past 18.I said things to make them angry 19.I spoke to them in a hostile or mean tone of voice 20.I insulted them with put downs 21.I ridiculed or made fun of them in front of others 22.I kept track of who they were with and where they were 23.I blamed them for the problem 24.I accused them of flirting with another person 25.I threatened to end the relationship 26.I monitored who my dating partner(s) talk to and who he/she is friends with using the Internet or a cell phone 27.I looked at my dating partner's private information on a computer or cell phone without his/her permission (like his/her personal email, instant messages, text history, call log, etc.) 28.I monitored my dating partner's whereabouts using the Internet or a cell phone (checking his/her Facebook “status”, calling or texting repeatedly to ask where he/she was, etc.)
Positive mental health: Mental Health Continuum – Short Form (MHC-SF) [44]	6 point Likert scale from ‘Never’ to ‘Everyday’; analyzed as mean score overall and by sub-scale (emotional well-being, psychological well-being, social well-being)	T1 T3	The next questions ask about your feelings in the past month. For each statement, please fill in the bubble that describes YOU best. During the past month, how often did you feel … Emotional: 1. ...happy? 2. ...interested in life? 3. ...satisfied with your life? Social: 4. ...that you had something important to contribute to society? 5.… that you belonged to a community (like a social group, your school, your neighborhood, your city, etc.)? 6....that our society is becoming a better place for people like you? 7.… that people are basically good? 8. ...that the way our society works makes sense to you? Psychological: 9.… that you liked most parts of your personality? 10. ...good at managing the responsibilities of your daily life? 11.… that you had warm and trusting relationships with others? 12....that you had experiences that challenged you to grow and become a better person? 13.… confident to think or express your own ideas and opinions? 14. ...that your life has a sense of direction or meaning to it?
Bullying perpetration: School Climate Bullying Survey – Bullying Behavior Sub-Scale (SCBS-BB) [45]	4 point Likert scale from ‘never’ to ‘several times per week’; dichotomized as any endorsement overall and by type	T1 T3	The next set of questions ask about your experiences with bullying in the last month. For this survey, bullying is defined as the use of one's strength or popularity to injure, threaten or embarrass another person. Bullying can be physical, verbal, social or electronic. It is not bullying when two students who are about the same in strength or power have a fight or argument. 1.Physical bullying involves repeatedly hitting, kicking, or shoving someone weaker on purpose. During the past month (30 days) at school: Ihave physically bullied or threatened to physically bully another student. 2.Verbal bullying involves repeatedly teasing, putting down, or insulting someone on purpose. During the past month (30 days) at school: I have verbally bullied another student. 3.Social bullying involves getting others repeatedly to ignore or leave someone out on purpose. During the past month (30 days) at school: I have socially bullied another student. 4.Cyber bullying involves using technology (cell phone, email, internet chat and posting, social media, etc.) to tease or put down someone. During the past month (30 days) at school or home: I have cyber bullied another student.
Friendship closeness: Network of Relationships Inventory – Relationship Qualities Version (NRI-RQV) [46]	5 point Likert scale from ‘never or hardly at all’ to ‘always or extremely much’; analyzed as mean score	T1 T3	BEST SAME-SEX FRIEND 1.How often do you spend fun time with this person? 2.How often do you tell this person things that you don't want others to know? 3.How happy are you with your relationship with this person? 4.How often do you turn to this person for support with personal problems? 5.How often does this person praise you for the kind of person you are? 6.How often do you and this person go places and do things together? 7.How often do you tell this person everything you are going through? 8.How much do you like the way things are between you and this person? 9.How often do you depend on this person for help, advice, or sympathy? 10.How often does this person seem really proud of you? 11.How often do you play around and have fun with this person? 12.How often do you share secrets and private feelings with this person? 13.How satisfied are you with your relationship with this person? 14.When you are feeling down or upset, how often do you depend on this person to cheer things up? 15.How much does this person like or approve of the things you do?
Homophobic name-calling: Homophobic Content Agent Scale (HCAT) [47]	5 point Likert scale from ‘never’ to’ ‘7 or more times’; analyzed as mean score for each target	T1T2 T3	Some kids call each other names such as gay, lesbo, fag, etc. How many times in the last week did you say these things to: 1.A friend 2.Someone I did not know 3.Someone I did not like 4.Someone I thought was gay 5.Someone I did not think was gay
Sexual health self-efficacy: Sexual Health-Efficacy Scale (SHSE) [48]	5-point Likert scale from ‘not at all confident’ to ‘extremely confident; analyzed as mean score	T1 T2 T3	Available from scale developer
Adherence to male role norms: Male Role Norms Inventory – Adolescent – Revised (MRNI-A-r) [49]	7-point Likert scale from ‘strongly disagree’ to ‘strongly agree’; analyzed as mean score overall and by sub-scale (avoidance of femininity, toughness, emotionally detached dominance)	T1 T2	Available from scale developer
Adolescent Masculinity Ideology in Relationships Scale (AMIRS) [50]	7-point Likert scale from ‘strongly disagree’ to ‘strongly agree’; analyzed as mean score overall	T1 T2	1.It's important for a guy to act like nothing is wrong, even when something is bothering him. 2.In a good dating relationship, the guy gets his way most of the time. 3.I can respect a guy who backs down from a fight. 4.It's ok for a guy to say no to sex. 5.Guys should not let it show when their feelings are hurt. 6.A guy never needs to hit another guy to get respect. 7.If a guy tells people his worries, he will look weak. 8.I think it's important for a guy to go after what he wants, even if it means hurting other people's feelings. 9.I think it is important for a guy to act like he is sexually active even if he is not. 10.I would be friends with a guy who is gay. 11.It's embarrassing for a guy when he needs to ask for help. 12.I think it's important for a guy to talk about his feelings, even if people might laugh at him.
Masculine Discrepancy Stress Scale [51]	5-point Likert scale from ‘disagree strongly’ to ‘agree strongly’; analyzed as mean score overall	T1 T2	1.I wish I were more “manly” 2.I wish I was interested in things that other guys find interesting 3.I worry that people judge me because I am not like the typical man 4.Sometimes I worry about my masculinity 5.I worry that women find me less attractive because I'm not as macho as other guys
Attitudes towards sexual minorities: Negativity Towards Sexual Minorities Scale (NTSM) [52]	7-point Likert scale from ‘strongly disagree’ to ‘strongly agree; analyzed as mean score	T1 T2	Available from scale developer
Dating abuse awareness: Dating Abuse Awareness Scale (DAAS) [36]	5-point Likert scale from ‘not abusive’ to ‘extremely abusive’; analyzed as mean score	T1 T2	Below is a list of experiences people might have in a dating relationship. Please rate each of the following actions towards a girlfriend or boyfriend as not abusive, a little abusive, somewhat abusive, very abusive or extremely abusive. 1.Name calling or insulting them 2.Telling them they're ugly or stupid 3.Making fun of them in front of other people 4.Telling them what to do all the time 5.Telling them which friends they can and can't see or talk to 6.Pressuring them not to break up with them 7.Not listening to what they have to say 8.Trying to convince them to have sex 9.Preventing them from leaving a room 10.Keeping tabs on them or spying on them 11.Threatening to hit them 12.Forcing them to have sex
Intentions to intervene with peers [36]	5-point Likert scale from ‘very unlikely’ to ‘very likely’; analyzed as mean score	T1 T2	How likely are YOU to do something to try and stop what's happening if a male friend or peer (someone your age) is: 1.Making rude or disrespectful comments about a girl's body, clothing, or makeup 2.Spreading rumors about a girl's sexual reputation, like saying “she's easy” 3.Fighting with a girl where he's starting to cuss or threaten her 4.Doing unwelcome or uninvited things toward a girl (or group of girls), such as howling, whistling, or making sexual gestures 5.Shoving, grabbing, or otherwise physically hurting a girl 6.Showing other people sexual messages or naked/sexual pictures of a girl on a cell phone or the Internet 7.Telling sexual jokes that disrespect women and girls 8.Taking sexual advantage of a girl (like touching, kissing, having sex with) who is drunk, high from drugs, or passed out
Help-seeking intentions: General Help Seeking Questionnaire (GHSQ), adapted [53]	7-point Likert scale from ‘extremely unlikely’ to ‘extremely likely’; analyzed as likelihood to seek help from each source	T1 T2	If you were having a personal or emotional problem, how likely is it that you would seek help from the following people? 1.Mental health professional (e.g., psychologist, social worker, school counsellor) 2.Teacher 3.Youth worker 4.I would not seek help from anyone
Drug use intentions: Drug Resistance Self-Efficacy (DRSE) [54]	5-point Likert scale from ‘disagree strongly’ to ‘agree strongly’; analyzed as mean score	T1 T2	I am confident that I can … 1.… find ways of reducing stress, that don't involve alcohol/drugs 2.… make friends with people who don't use alcohol/drugs 3.… resist the temptation to use alcohol/drugs when others around me are using 4.… find things to do that I enjoy but that don't involve alcohol/drugs 5.… avoid situations and people where alcohol/drugs are present