Crystal Smit

Social Network Intervention 2 35 at the time they filled in the baseline and post-intervention questionnaire. The children had to indicate how thirsty they were at that moment on a 4-point scale, ranging from 1 = ‘not thirsty at all’ to 4 = ‘very thirsty’. Statistical Analysis Data were analyzed using SPSS version 21 (SPSS, Inc., Chicago, IL, US). Alpha was set at p < .05. First, independent-samples t -tests and Pearson’s chi square tests were performed to examine whether the randomization resulted in a balanced distribution across the control and intervention condition. To determine whether we had to control for age, sex, and thirst in the main analysis, Pearson’s correlations were performed for these variables with water consumption, SSB consumption, and water drinking intentions. For the main analyses, we used a two-way repeated measure MANCOVA with time (baseline vs. post-intervention) and condition (intervention vs. control) as the independent variables and three dependent variables: water consumption, SSB consumption, and water drinking intentions. Statistically significant main effects on condition or time, or an interaction between time and condition on water drinking, SSB consumption, and water drinking intentions were further examined by contrast comparisons or pairwise comparisons with Bonferroni correction. The same analyseswere repeatedwithout the influence agents to examinewhether the effect of the intervention was driven by the behaviors and intentions of the influence agents. Furthermore, paired sample t -tests were carried out to explore the effect of the training on the water and SSB consumption and water drinking intentions of the influence agents. Effect sizes for the F -tests were expressed as partial eta-squared ( p η 2 ) and interpreted as small, medium, and large based on the values .01, .06, and .14, respectively (Stevens, 2009). RESULTS Randomization Check To check whether there were differences between the control and intervention condition on age, thirst, water consumption, SSB consumption, and water drinking