Author(s) (study name) | Country | Study design | Sample size and characteristics | Data collection methods | Method(s) for collecting and summarising social network data | Method(s) for analysing social network data | Eating behaviour and/or bodyweight measures | Key findings |
Cohen-Cole and Fletcher (2008)22 (National Longitudinal Study of Adolescent Health (Add Health)) | USA | Longitudinal | Schools: N/S; students: n=1988 | School-based and in-home surveys |
| Logistic and OLS regression | Obesity | Odds that an ego becomes obese if his or her ‘best friend’ is obese: unadjusted=0.8, after adjusting for school-specific trends=0.51, after adjusting for school-specific trends and individual fixed effects=NSE |
de la Haye et al (2009)30 | Australia | Cross-sectional | Schools: n=2; students: n=385 (age 13–15 years; 202 males, 183 females) | School-based survey | Respondents listed the first and last names of all their ‘close friends’ in their school grade (defined as friends they ‘hang around with’ most) | Exponential random graph modelling, stratified by gender | High-calorie food consumption (fast food, savoury snack foods, sweet snack foods, high-calorie drinks) |
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Fowler and Christakis (2008)23 (Add Health) | USA | Longitudinal | Schools: N/S; students: n=1988 | School-based and in-home surveys | Respondents asked to list up to 10 of their closest friends (5 male, 5 female) | Logistic regression | Obesity |
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Halliday and Kwak (2009)25 (Add Health) | USA | Longitudinal | Schools: n=16; students: wave 1, n=4617; wave 2, n=2970 (mean age 15 years; 48% male, 52% female; ethnicity: 55% Caucasian, 19% African–American, 12% Asian; SES: single-parent household ∼30%) | School-based and in-home surveys | Respondents asked to list up to 10 of their closest friends (5 male, 5 female) | Logistic regression (school fixed effects) |
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Hutchinson and Rapee (2007)29 | Australia | Cross-sectional | Schools: n=10; students: n=1094 (mean age 12.3 years; 100% female; SES: 84% born in Australia, 83% English first language, 82% two-parent family) | School-based survey |
| MANCOVA within friendship cliques |
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Paxton et al (1999)28 | Australia | Cross-sectional | Schools: n=6; students: n=523 (age 15–16 years, 100% female) | School-based survey |
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Pike (1995)26 | USA | Cross-sectional | Schools: n=3; students: n=410 (mean age 16 years, range 14–19 years; 100% female) | School-based survey. | Respondents asked to identify up to 6 of their closest female friends |
| Bulimic symptoms |
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Strauss and Pollack (2003)21 (Add Health) | USA | Cross-sectional | Students: n=17 557 (7th to 12th Grade; BME: 18% African–American, 12% Hispanic 12%; SES: 29% single-parent household) | School-based and in-home surveys |
| Multivariate regression analysis | Overweight (BMI above 95th percentile) |
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Trogdon et al (2008)24 (Add Health) | USA | Cross-sectional | Schools: n=16; students: n=3702 (mean age 16.1 years) | School-based and in-home surveys | Respondents asked to list up to 10 of their closest friends (5 male, 5 female) | Multivariate regression analysis |
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Valente et al (2009)27 | USA | Cross-sectional | Schools: n=4; students: n=617 (age 11–15 years; 36% male, 64% female; ethnicity: 36% Asian, 30% Hispanic, 12% Caucasian 12%, 12% mixed, 6% other, 3% African–American | School-based survey | Respondents asked to nominate friends in their class | Random-effect logistic regression modelling, with individuals nested by school-class | Overweight (BMI above 95th percentile) |
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BME, black and minority ethnicity; BMI, body mass index; MANCOVA, multivariate analyses of covariance; MPEADE, model parameter estimates for absolute difference effects; N/S, not stated; NSE, no significant effect; OLS, ordinary least squares; Pajek, large network analysis program (http://pajek.imfm.si/doku.php); SAS/IML, nInteractive matrix programming with integration to R (SAS Institute, Cary, North Carolina, USA); SES, socioeconomic status; UCINET, social network analysis program (Analytic Technologies, Lexington, Kentucky, USA).