摘要
同伴是影响初中生学业成绩的重要因素。国内已有研究对这一问题进行过探讨,但在解决内生性方面还有一定的不足。因此,本文利用同一班级相邻两年的初中生发育成熟度的自然变化这一随机效应来识别由于青春期发育成熟度变化带来的同伴效应,采用一阶差分和分位数回归的策略,解决了一般回归分析中存在的内生性问题。研究发现:女生发育成熟度与学生成绩为显著的负向关联,男生发育成熟度与学生成绩为显著的正向关联,这说明男女生发育成熟度对初中生学业成绩的影响具有性别差异。此外,同伴效应还具有异质性,总体来看,班级女生发育成熟度越低,越有利于学生成绩的提高;班级男生发育成熟度越高,越有利于学生成绩的提高。本研究的发现对于适龄儿童入学年龄的调整有一定的政策含义。
Peer is an important factor affecting junior high school students' academic performance. Domestic research has discussed this issue,but there are still some shortcomings in eliminating endogeneity. This paper uses the changes of the puberty maturity of junior high school students in the same class for two years to identify peer effects which are derived from the changes of the puberty maturity of junior high school students. The first difference and quantile regression strategies are used to empirically test the peer effects of junior high school students in China,solving the endogeneity problem of general OLS. The study found that there is a very significant positive correlation between the boys' puberty maturity and the students' average scores,and there is a very significant negative correlation between the girls' puberty maturity and the students' average scores. This shows that peers' puberty maturity has a gender difference in the impact of junior high school students' academic performance. Moreover,peer effect is heterogeneous. The smaller in the puberty maturity of the girls in the class,and the better the class average grade. The greater in the puberty maturity of the boys in the class,and the better the class average grade.
引文
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(1)指填写了初潮年龄的男生和填写了首次遗精年龄的女生、未作答首次遗精年龄的男生和未作答初潮年龄的女生样本以及初潮时间、首次遗精时间早于9岁的样本。
(1)只考虑进入青春期学生的成绩时(如:表4第3、4列),有效样本为30所学校的56个班的2589名学生。
(2)女:(18. 288-13. 092)/13. 092=0. 3969;男:(7. 903-4. 502)/4. 502=0. 7554;所有学生:(26. 191-17. 447)/17. 447=0. 5012
(3)CEPS采用标准分,两轮调查学生认知能力得分分别分布在-2. 029分~2. 710分、-3. 137分~2. 063分。
(4)同一班级内进入青春期(即出现首次遗精或初潮)的学生数作为学生发育成熟度的代理变量。
(5)没接受过任何教育、小学、初中、中专/技校、职高、普高、大专、大学本科、研究生及以上分别记为0年、6年、9年、12年、12年、12年、12 年、16年、19年。
(6)学校性质为分类变量,1-4分别表示公立学校、民办公助、普通民办学校、民办打工子弟学校。
(7)有一所学校在第一轮调查中未填写学校排名,所以表1“七年级学校排名”的样本数为2560。
(1)有研究表明,女生初潮早晚、男生首次遗精早晚受到遗传、营养状况、经济收入水平、压力等因素的影响,而这些因素对男、女生发育成熟早晚的影响大都可归结为家庭经济社会地位的差异所导致的营养差异。
(1)在语文压力大的分组中,发育成熟度对学生成绩的影响均不显著,这可能与其人数较少有关。