摘要：We investigated whether “hidden” (or unobserved) social networks were evident in a 2011 physical activity behavior change intervention in Belfast, Northern Ireland. Results showed evidence of unobserved social networks in the intervention and illustrated how the network evolved over short periods and affected behavior. Behavior change interventions should account for the interaction among participants (i.e., social networks) and how such interactions affect intervention outcome. Complex behavior change interventions have unintentional and unobserved consequences and effects that must be captured to help us fully understand mechanisms of behavior change. 1 For example, many interventions do not account for the interaction among participants (i.e., social networks) and how such interactions affect intervention outcome. 2 Berkman 3 illustrates how social networks affect health through social interactions at the microlevel affecting behavior at the meso- and macrolevels, and previous research has helped us understand the effect of social networks on a range of health behaviors. 4–13 We argue that “hidden” (or unobserved) social networks are inherent in behavior change interventions, particularly in cluster trials, and hypothesize that such networks affect the outcome of behavior change interventions. We investigated (1) whether social networks were evident in a physical activity behavior change intervention, and (2) if evident, what the characteristics and evolution of the network structure were over time.
