Is Weight Influenced by Peers: An Empirical Research Based on Classroom Units

doi:10.16382/j.cnki.1000-5560.2023.12.008

Abstract

Abstract:

The research of peer effects on weight is important for clarifying the generating process of abnormal weight, as well as promoting the social governance of adolescent physical health development. Based on the social interaction theory and a combination of data from the 2013-2014 and 2014-2015 academic years of the China Education Panel Survey (CEPS), this study aimed to identify the weight peer effect of adolescents within classes and the underlying mechanisms. It was found that there was a weight peer effect within the class unit, with peer mean BMI and peer overweight and obesity rates significantly and positively affecting individual BMI. The results consistently held after controlling for contextual and corrlated effects, performing instrumental variable treatment, and conducting robustness tests. Further mechanism analysis showed that weight perception played a moderating role in the occurrence of the weight peer effect, and that overestimating one’s own weight significantly weakened the weight peer effect, while underestimating one’s own weight has no effect on it. Accordingly, it was demonstrated that the countermeasures against abnormal weight of adolescents in the school context have good externalities, and suggestions such as reasonable allocation of health education resources, enrichment of health education work content, and close attention to social experiences of student groups were proposed.

Key words: weight, overweight, obesity, peer effect, classroom

Sihui Du, Gang Cheng, Wenshan Yu. Is Weight Influenced by Peers: An Empirical Research Based on Classroom Units[J]. Journal of East China Normal University(Educational Sciences), 2023, 41(12): 85-99.

Figures/Tables 7

分类	名称	操作化定义	平均值	标准差	样本量
被解释变量	个体BMI	个体体重（kg）÷身高（m）的平方	19.390	3.684	6875
核心解释变量	同伴平均BMI	班级内其他个体的平均BMI	19.390	1.015	6875
核心解释变量	同伴超重肥胖率	班级内其他个体的超重肥胖率，按2014年《国家学生体质健康标准》进行判断与计算	0.153	0.094	6875
基准控制变量	性别	男=1，女=0	0.512	0.500	6875
	户口	农业=1，其他=0	0.467	0.499	6628
	是否独生子女	是=1，否=0	0.508	0.500	6813
	是否寄宿	是=1，否=0	0.225	0.418	6745
	健康自评情况	“很不好”=1至“很好”=5	3.890	0.934	6834
	体育锻炼时间	每周参与体育锻炼的小时数	2.693	3.442	6875
	致胖食品食用频率	“从不”=1至“总是”=5	2.716	0.805	6826
	致胖饮品饮用频率	“从不”=1至“总是”=5	2.862	0.865	6806
	父母最高受教育年限	父母双方受教育年限的最大值	11.132	3.404	6875
	家庭经济条件自评	“非常困难”=1至“很富裕”=5	3.003	0.589	6845
情境效应	同伴身材自评情况	“很瘦”=1至“很胖”=5，取班级内其他个体作答情况的平均值	3.181	0.179	6875
关联效应	基线时期BMI	基线时期个体体重（kg）÷身高（m）的平方	18.599	3.472	6214
	班级规模	班级总人数	44.113	11.305	6875
	班级排名	“最差”=1至“最好”=5，以各班班主任作答结果为准	3.464	1.020	6875
	班主任性别	男=1，女=0	0.312	0.464	6875
	班主任教龄	班主任从事教学工作的连续年限	16.446	8.206	6875
	学校排名	“最差”=1至“最好”=5，以各校校领导作答结果为准	4.057	0.793	6875
	学校位置	“农村”=1至“市/县城的中心城区”=5，以校领导作答结果为准	2.230	1.591	6875
	学校运动环境	操场、运动场、体育馆、游泳池的建设数量	2.112	0.705	6875
工具变量	基线时期同伴平均BMI	基线时期班级内其他个体的平均BMI	18.588	1.038	6875
工具变量	同伴与祖辈同住比例	班级内其他个体与祖辈同住的比例	0.307	0.133	6875
调节变量	是否错误感知自身体重	是=1，否=0	0.474	0.499	6836
	是否高估自身体重	是=1，否=0	0.192	0.394	6836
	是否低估自身体重	是=1，否=0	0.282	0.450	6836

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	班级平均BMI		班级超重肥胖率
	(1)	(2)	(3)	(4)
男生比例	2.973*	2.854**	0.181	0.167*
	(1.148)	(1.043)	(0.094)	(0.084)
农业户口学生比例	?0.594	?0.295	?0.065	?0.033
	(0.450)	(0.486)	(0.043)	(0.042)
平均父母最高受教育年限	0.030	0.114	?0.002	0.005
	(0.088)	(0.092)	(0.008)	(0.008)
平均家庭经济条件	0.475	0.308	0.074*	0.063
	(0.520)	(0.552)	(0.036)	(0.040)
班级规模	?0.018*	?0.011	?0.001*	?0.001
	(0.007)	(0.008)	(0.001)	(0.001)
班级排名	?0.035	?0.048	?0.005	?0.006
	(0.073)	(0.078)	(0.006)	(0.007)
班主任教龄	0.004	0.005	0.001	0.002
	(0.010)	(0.010)	(0.001)	(0.001)
学校层面特征		是		是
样本量	169	169	169	169
VIF均值	2.15	2.22	2.15	2.22

	个体BMI					个体BMI
	(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)
同伴平均BMI	0.674***	0.637***	0.688***	0.402***	0.400***
同伴平均BMI	(0.033)	(0.041)	(0.044)	(0.053)	(0.054)
同伴超重肥胖率						6.768***	6.279***	6.550***	3.588***	3.557***
同伴超重肥胖率						(0.502)	(0.590)	(0.628)	(0.641)	(0.653)
社会乘数	—	—	—	—	1.667	—	—	—	—	—
个体及家庭特征		是	是	是	是		是	是	是	是
情境效应			是	是	是			是	是	是
关联效应：相关群体				是	是				是	是
关联效应：共同环境					是					是
样本量	6875	6307	630	5725	5725	6875	6307	6307	5725	5725
R²	0.034	0.041	0.042	0.357	0.358	0.030	0.036	0.036	0.354	0.355

	个体BMI				个体BMI
	IV-2SLS	IV-GMM	IV-2SLS	IV-GMM	IV-2SLS	IV-GMM	IV-2SLS	IV-GMM
	(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)
同伴平均BMI	0.715***	0.719***	0.232**	0.237***
同伴平均BMI	(0.041)	(0.041)	(0.097)	(0.097)
同伴超重肥胖率					8.017***	8.157***	2.883**	2.949**
同伴超重肥胖率					(0.791)	(0.786)	(1.193)	(1.192)
社会乘数	—	—	1.302	1.311	—	—	—	—
第一阶段回归
基线时期同伴平均BMI	0.696***	0.696***	0.566***	0.566***	0.062***	0.062***	0.049***	0.049***
基线时期同伴平均BMI	(0.058)	(0.058)	(0.062)	(0.062)	(0.005)	(0.005)	(0.005)	(0.005)
同伴与祖辈同住比例	?0.065	?0.065	?0.087	?0.087	0.013	0.013	0.028	0.028
同伴与祖辈同住比例	(0.460)	(0.460)	(0.416)	(0.416)	(0.044)	(0.044)	(0.041)	(0.041)
个体及家庭特征	是	是	是	是	是	是	是	是
情境效应			是	是			是	是
关联效应		是	是				是	是
检验结果
内生性检验	6.359	6.359	2.864	2.864	11.093	11.093	0.202	0.202
p值	(0.012)	(0.012)	(0.091)	(0.091)	(0.001)	(0.001)	(0.653)	(0.653)
弱工具变量检验	3008.476	3008.476	1274.871	1274.871	2757.574	2757.574	1123.159	1123.159
过度识别检验	2.291	2.291	1.940	1.940	2.431	2.431	1.200	1.200
p值	(0.130)	(0.130)	(0.164)	(0.164)	(0.119)	(0.119)	(0.273)	(0.273)
样本量	6307	6307	5725	5725	6307	6307	5725	5725

	个体BMI			个体BMI
	(1)	(2)	(3)	(4)	(5)	(6)
同伴平均BMI	0.497***	0.386***	0.474***
同伴平均BMI	(0.064)	(0.064)	(0.064)
同伴超重肥胖率				4.661***	3.305***	4.584***
同伴超重肥胖率				(0.725)	(0.682)	(0.667)
错误感知自身体重	3.768*			0.073
错误感知自身体重	(1.720)			(0.148)
核心解释变量*错误感知自身体重	?0.208*			?2.278*
核心解释变量*错误感知自身体重	(0.089)			(0.900)
高估自身体重		5.711***			0.037
高估自身体重		(1.288)			(0.118)
核心解释变量*高估自身体重		?0.322***			?3.831***
核心解释变量*高估自身体重		(0.067)			(0.706)
低估自身体重			?0.746			0.073
低估自身体重			(3.433)			(0.265)
核心解释变量*低估自身体重			0.051			1.266
核心解释变量*低估自身体重			(0.177)			(1.610)
个体及家庭特征	是	是	是	是	是	是
情境效应	是	是	是	是	是	是
关联效应	是	是	是	是	是	是
样本量	5708	5708	5708	5708	5708	5708
R²	0.360	0.359	0.364	0.357	0.356	0.361

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