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Objective: Sample size and statistical power calculation should consider clustering effects when schools are the unit of randomization in intervention studies. The objective of the current study was to investigate how student outcomes are clustered within schools in an obesity prevention trial. Method: Baseline data from the Food, Health & Choices project were used. Participants were 9- to 13-year-old students enrolled in 20 New York City public schools (n = 1,387). Body mass index (BMI) was calculated based on measures of height and weight, and body fat percentage was measured with a Tanita® body composition analyzer (Model SC-331s). Energy balance-related behaviors were self-reported with a frequency questionnaire. To examine the cluster effects, intraclass correlation coefficients (ICCs) were calculated as school variance over total variance for outcome variables. School-level covariates, percentage students eligible for free and reduced-price lunch, percentage Black or Hispanic, and English language learners were added in the model to examine ICC changes. Results: The ICCs for obesity indicators are: 0.026 for BMI-percentile, 0.031 for BMI z-score, 0.035 for percentage of overweight students, 0.037 for body fat percentage, and 0.041 for absolute BMI. The ICC range for the six energy balance-related behaviors are 0.008 to 0.044 for fruit and vegetables, 0.013 to 0.055 for physical activity, 0.031 to 0.052 for recreational screen time, 0.013 to 0.091 for sweetened beverages, 0.033 to 0.121 for processed packaged snacks, and 0.020 to 0.083 for fast food. When school-level covariates were included in the model, ICC changes varied from -95% to 85%. Conclusions: This is the first study reporting ICCs for obesity-related anthropometric and behavioral outcomes among New York City public schools. The results of the study may aid sample size estimation for future school-based cluster randomized controlled trials in similar urban setting and population. Additionally, identifying school-level covariates that can reduce cluster effects is important when analyzing data.

Fruit and vegetable (FV) attitudes and norms have been shown to influence intake in youth; yet research with low-income youth and studies supplementing self-report with objective measures of intake are lacking. Cross-sectional survey data on self-rated FV intake, FV attitudes, and FV norms were collected in a sample of 116 youth attending a residential summer camp serving low-income families. FV intake also was estimated by direct observation. Differences between self-rated and observed FV intake, perceived and observed peer intake, and perceived and peer-reported attitudes toward eating FVs were assessed with paired samples t tests. The role of FV attitudes, descriptive norms (perceived peer FV intake), injunctive norms (perceived peer attitudes toward eating FVs), and actual norms (observed peer FV intake and peer-reported FV attitudes) in predicting FV intake also was examined with multiple regression analysis. Youth misperceived their own and their peers' FV intake (i.e., overestimated intake of fruit and underestimated intake of vegetables) and believed that peers held less favorable attitudes toward eating FVs than was the case. The models predicting self-rated intake were significant, accounting for 34% of the variance in fruit intake and 28% of the variance in vegetable intake. Attitudes and descriptive norms were positively associated with FV intake, and observed peer fruit intake was negatively associated with fruit intake. Findings suggest that in low-income youth, FV attitudes, descriptive norms, and normative peer behavior predict perceived but not actual intake. Youth may benefit from intervention to promote favorable FV attitudes and norms. A focus on descriptive norms holds promise for improving self-rated intake in this population.

This study identified mediators of a Transtheoretical Model (TTM) intervention to increase fruit and vegetable consumption among economically disadvantaged African American adolescents (N = 549). Single-and multiple-mediator models were used to determine whether pros, cons, self-efficacy, and stages of change satisfied four conclusions necessary for establishing mediation of intervention effects on youths' dietary behavior. All four conclusions were satisfied for stages of change and pros in the single-mediator models and for stages in the multiple-mediator model. Stages mediated 31% of the intervention effect, and pros mediated 7% of the intervention effect in the single-mediator models. In the multiple-mediator model, stages accounted for 72% of the intervention effect. Findings add to the limited data on mediating variables in TTM dietary intervention programs. Replication studies are needed before it can be concluded that stages of change and pros are consistent mediators of TTM intervention program effects. (Contains 2 tables.)

This study evaluates the efficacy of Keepin' It Safe, a theory-based, gender-specific, CD-ROM-mediated HIV prevention program for urban, early adolescent girls. Intervention effects were examined in a randomized, pretest-posttest wait-list control-group design. Changes in HIV/AIDS knowledge, protective attitudes, and skills for reducing HIV risk-related sexual behaviors were tested using linear regression models that were controlled for baseline values of each outcome. Recruited through youth services agencies located in the greater New York City area, study participants comprised 204 adolescent girls aged 11-14 years. Girls exposed to Keepin' It Safe, relative to wait-list control girls, increased their HIV/AIDS knowledge, perceived efficacy and enjoyment of abstinence, perceived efficacy and enjoyment of condoms, and sexual assertiveness, suggesting that a theory-based, gender-specific, CD-ROM-mediated HIV prevention program can enhance knowledge, protective attitudes, and skills for reducing HIV risk-related sexual behaviors among urban early-adolescent girls.

The criterion validity of a prototype version of the Healthy Eating Self-monitoring Tool (HEST), a computer-mediated food record for assessing fruit and vegetable consumption among economically disadvantaged black adolescents, was examined. A qualitative design employing focus group methodology gathered data for informing the design of the HEST (n=32) and the selection of screens for inclusion in the measure (n=6). The criterion validity of the HEST was examined in a cross-sectional design (n=60) using direct observation of intake as the validation standard. Pearson correlations and paired-samples t tests compared mean observed and mean HEST-recorded servings of fruits and vegetables measured over three consecutive meals. Correlations were significant for seven of the nine HEST items, ranging from r-0.41 (P<0.01) to r=0.65 (P<0.001); for the overall measure, the correlation was r=0.51 (P<0.001). Paired-samples t tests confirmed the absence of differences between observed and recorded intake for approximately half of the HEST items. The HEST offers a viable alternative to traditional paper-and-pencil food records. With further development and validation, the HEST can be used to measure fruit and vegetable consumption among economically disadvantaged black adolescents.

Objective: This study tested a CD-ROM intervention with and without a parent involvement component to reduce risk of alcohol use among an urban sample of early adolescents. Method: Youths (N = 514, mean age 11.5 years at recruitment) were assigned randomly by community site to receive the CD-ROM intervention, the CD-ROM plus parent intervention, or no intervention. All youths completed pretest, posttest and three annual follow-up measurements. After pretesting, youths and parents received their respective interventions. Results: Main effects of the intervention and for measurement occasion as well as interaction effects of the intervention by measurement occasion were seen for substance use and related outcomes. Over time, youths in all 3 groups reported increased use of alcohol, tobacco and marijuana; youths who received the interventions reported smaller increases than control youths. At 3-year follow-up, alcohol use was lower for CD-ROM plus parent intervention youths than for CD-ROM only youths, who, in turn, reported less use than controls. Cigarette use was lower for youths in either intervention group than in the control group at posttest and at 1-, 2- and 3-year follow-ups. Marijuana use was lower for youths in either intervention than for controls at 1-, 2- and 3-year follow-ups. Youths in both intervention groups outperformed control youths at posttest and at 1- and 3-year follow-ups on levels of negative and peer influence toward substance use. Finally, at the 3-year follow-up, youths in the CD-ROM plus parent intervention group reported more family involvement in their alcohol use prevention efforts than did youths in the CD-ROM group, who, in turn, reported more positive levels of family involvement than youths in the control group. Conclusions: Study findings modestly support the CD-ROM intervention with and without the parent intervention to reduce alcohol use risks among urban early adolescents., CONSIDERABLE RESEARCH has been invested in discovering effective approaches to prevent alcohol use among American youth. Most approaches use theory-driven principles to help young people resist peer pressure, offset media [...]