Centre for Exercise, Nutrition & Health, School for Policy Studies, University of Bristol, Bristol BS8 1TP, UK.
Soc Sci Med. 2011 Jul;73(1):6-12. doi: 10.1016/j.socscimed.2011.04.018. Epub 2011 May 18.
Despite the known health benefits, the majority of children do not meet physical activity guidelines, with past interventions to increase physical activity yielding little success. Social and friendship networks have been shown to influence obesity, smoking and academic achievement, and peer-led interventions have successfully reduced the uptake of adolescent smoking. However, the role of social networks on physical activity is not clear. This paper investigates the extent to which friendship networks influence children's physical activity, and attempts to quantify the association using spatial analytical techniques to account for the social influence. Physical activity data were collected for 986 children, aged 10-11 years old, from 40 schools in Bristol, UK. Data from 559 children were used for analysis. Mean accelerometer counts per minute (CPM) and mean minutes of moderate to vigorous physical activity per day (MVPA) were calculated as objective measures of physical activity. Children nominated up to 4 school-friends, and school-based friendship networks were constructed from these nominations. Networks were tested to assess whether physical activity showed spatial dependence (in terms of social proximity in social space) using Moran's I statistic. Spatial autoregressive modelling was then used to assess the extent of spatial dependence, whilst controlling for other known predictors of physical activity. This model was compared with linear regression models for improvement in goodness-of-fit. Results indicated spatial autocorrelation of both mean MVPA (I = .346) and mean CPM (I = .284) in the data, indicating that children clustered in friendship groups with similar activity levels. Spatial autoregressive modelling of mean MVPA concurred that spatial dependence was present (ρ = .26, p < .001), and improved model fit by 31% on the linear regression model. These results demonstrate an association between physical activity levels of children and their school-friends, and indicate that spatial modelling is an informative method for incorporating the influence of school social structure into physical activity analysis.
尽管人们知道体育活动对健康有益，但大多数儿童都不符合体育活动指南的要求，过去增加体育活动的干预措施收效甚微。社交和友谊网络已被证明会影响肥胖、吸烟和学业成绩，而以同伴为主体的干预措施已成功减少了青少年吸烟的比例。然而，社交网络对体育活动的影响尚不清楚。本文研究了友谊网络对儿童体育活动的影响程度，并尝试使用空间分析技术来量化这种关联，以考虑社交影响。为了收集英国布里斯托尔 40 所学校 986 名 10-11 岁儿童的体育活动数据，使用了 559 名儿童的数据进行分析。每分钟计步器计数（CPM）和每天中等至剧烈体育活动的平均分钟数（MVPA）被计算为体育活动的客观测量值。儿童最多提名 4 名校友，然后根据这些提名构建基于学校的友谊网络。通过莫兰 I 统计量测试网络，以评估体育活动是否表现出空间依赖性（社交空间中的社会接近度）。然后使用空间自回归模型评估空间依赖性的程度，同时控制其他已知的体育活动预测因素。为了提高拟合优度，将该模型与线性回归模型进行了比较。结果表明，数据中 MVPA 的均值（I =.346）和 CPM 的均值（I =.284）存在空间自相关，表明儿童在具有相似活动水平的友谊群体中聚集。MVPA 均值的空间自回归模型也表明存在空间依赖性（ρ =.26，p <.001），并且比线性回归模型提高了 31%的拟合优度。这些结果表明，儿童的体育活动水平与其校友之间存在关联，并表明空间模型是将学校社会结构的影响纳入体育活动分析的一种有效方法。
