| Droomers M et al. 2005 [25] | New Zealand, Number and type of schools not stated, April 1972, and March 1973 | Longitudinal study | Data derived from Dunedin multidisciplinary health behavior project 481 boys 466 girls | Longitudinal Logistic GEE |
| Eengels RC et al. 2005 [26] | Netherlands, 11 Secondary schools in 2004 | Cross-sectional and short term longitudinal follow up | Data derived from a large scale survey in Netherlands 929 boys 932 girls | Binary logistic regression |
| El-Roueiheb Z et al. 2008 [27] | Beirut, Lebanon, 3 Public, 10 private schools from 2003-04 | Cross-sectional | Random sampling stratified by district within Beirut to select schools. All students were interviewed from schools 1089 boys 1328 girls | Multivariable regression analysis with missing data |
| Ellickson PL et al. 2008 [28] | California and Oregon, USA, 30 Secondary schools from 2000-2005 | longitudinal study over 5 years, | Data derived from ALERT project 1960 adolescents for smoking analysis. 2000 for problem behaviour analysis | Multivariate regression |
| Ennett ST et al. 2008 [29] | North Carolina USA, Wave 1: 8 middle schools, 2 comprehensive k-8 schools, 3 alternative schools Wave 2: 6 high schools, Middle & high grade from 2002-2004 | Longitudinal study | Convenience sampling Wave 1: 5220 boys and girls Wave 5: 5017 | Three level hierarchical growth models, Bayesian information criterion (BIC), Random intercept and random effect model |
| Faeh D et al. 2006 [30] | Seychelles, Indian ocean, 10 public schools 2 private schools, from global youth tobacco survey | Cross-sectional | Two stage cluster sampling design to obtain students Schools: probability proportional to school size Student: equal probability sampling 620 boys 654 girls | Percentage or proportion and CI |
| Finkelstein DM et al. 2006 [31] | Cincinnati, Ohio, USA, 1public high& 1 junior high public schools, date of study not mentioned. | Longitudinal study | Not stated 494 boys 527 girls | Chi-squared test, ANOVA with Tukey’s test, logistic regression analysis’ and GEE |
| Glanz K et al. 2007 [32] | Hawaii, 5 states Oahu, the big island of Hawaii, Maui, Molokai and Kawi, 22 Public & private schools from 2000-2002 | Cross-sectional | Convenience sampling 844 boys 851 girls | Chi.-square & t-test, GEE, PROC logistic regression |
| Grenard JL et al. 2006 [33] | China 7 cities, Hanbin, Shenyang, Wuhan, Chengdu, Kunming, & Hangzhou, Qingdao, 147 Middle schools & high schools, date of study not mentioned | Longitudinal study 1 year | Multistage cluster sampling 6991 boys 7387 girls | Chi-squared test t-test, paired t-test, Multilevel analysis & ICC, generalized linear mixed models |
| Grotvdt L et al. 2008 [34] | 6 countries in Norway including Oslo, 2 Southern inland 3 Northern countries, Public and private schools from 2000-04 | Cross-sectional | Convenience sampling 7762 boys 7768 girls | Generalized linear model with binominal distribution |