Table 4.

General characteristics and prevalence of bullying observed in the studies selected during the SLR

Country	Year	Authors	Title	Detection mode	Sample and age class	Bullying Prevalence
Denmark, Finland, Greenland, Iceland, Norway, Sweden	2019	Amarsson et al. [21]	Cyberbullying and traditional bullying among Nordic adolescents and their impact on life satisfaction	HBSC 2013/2014 (single item: “How often have you been bullied at school in the past couple of months?”)	32,210 students (11, 13 and 15 y.o.)	Norwegian Males: 2.7–7.8% Females: 3.1–5.2% Danish M: 2.7–8.0% F: 2.7–7.3% Finnish M: 6.4–12.6% F: 6.5–8.2% Greenlander M: 13.0–26.4% F: 13.7–18.6% Icelandic M: 1.4–6.9% F: 0.3–5.3% Swedish M: 2.1–3.5% F: 2.1–5.7%
Iceland	2018	Garmy et al. [22]	Bullying in School-aged Children in Iceland: A Cross-sectional Study	HBSC 2013/2014 in Iceland	11,018 students (11, 13 and 15 years old)	5.6%
Australia	2017	Thomas et al. [23]	Prevalence and correlates of bullying victimization and perpetration in a nationally representative sample of Australian youth	Single item: “In the past 12 months, how often were you bullied or cyberbullied by another person or group of young people?”	2,967 (11–14 y.o.)	15.5%
China	2017	Han et al. [24]	School Bullying in Urban China: Prevalence and Correlation with School Climate	Ten items on physical, verbal bullying and observers phenomena	1,020 middle school students	Victims: 26.10% Observers: 28.90% (aggregated data)
United Kingdom	2017	Muijs et al. [25]	Can schools reduce bullying? The relationship between school characteristics and the prevalence of bullying behaviors	For students: The Olweus Bully‐Victim Questionnaire (OBVQ). For teachers: 65 items-questionnaire based on Kyriakides (2014) scales	Survey conducted in 35 primary schools (1,411 last year's students and their 68 teachers)	Victims: 21% Actors: 11%
United Kingdom	2017	Bevilacqua et al. [26]	The role of family and school-level factors in bullying and cyberbullying: a cross sectional study	Gatehouse Bullying Scale (12 items)	6,667 students from 40 middle schools	Male: 9.99% Female: 13.61%
USA (Maryland)	2017	Waarsdorp et al. [27]	Ten-Year Trends in Bullying and Related Attitudes Among 4th- to 12th-Graders	10 years survey; anonymous and 13 items questionnaire	246,306 students in 109 schools of Maryland	28.5% in 2005 13.4% in 2014
Vietnam	2017	Le et al. [28]	Temporal patterns and predictors of bullying roles among adolescents in Vietnam: a school-based cohort study	Two anonymous questionnaires; single item: “How often have you been bullied in any way during the last six months?”	1,424 middle and high school students	48.3%: not involved at all; 22.7% victims only; 6.9% bullies only; 22% bully-victims After six months: 62.1% not involved; 17.6% victims only; 4.7% bullies only; 15.5% bully-victims
Spain	2016	Sanchez-Quelia et al. [29]	Trend analysis of bullying victimization prevalence in Spanish adolescent youth at school	Based on HBSC 2014 in Spain	15,728 (11–12 y.o.)	5.5% (reported) 23.6% (observed)
U.S.A	2015	Huang et al. [30]	The impact of definition and question order on the prevalence of bullying victimization using student self-reports	Anonymous, online, 100 items-survey	17,301 students attending 119 high schools	Bullying (overall): 9.84% Vs 13.53% cases Vs controls
Italy	2014	National survey [31]	Health Behaviour in School-aged Children	A single item within a broader nationwide questionnaire, mainly focused on habits and lifestyles	4,072 (11–15 y.o.)	14%
Macedonia	2007	WHO-Unicef-CDC [32]	Global school-based student health survey (GSHS)	Single item: “During the past 30 days, on how many days were you bullied?”	2,114 students (13–15 y.o.) in 30 schools	10.1%
Tajikistan	2006	WHO-Unicef-CDC [33]	Global school-based student health survey (GSHS)	Single item: “During the past 30 days, on how many days were you bullied?”	9,714 students (13–15 y.o.) in 99 schools	7.4%