关键词: 低生育率, 同胞性别结构, 教育水平, PSM

Abstract: Low fertility is one of the significant demographic characteristics of our country currently. Our government is easing the birth policy step-by-step for optimizing the demographic structure and promoting the balanced development of population. Nonetheless, the loose birth control policy can't improve the birth rate. Many scholars find that the fertility rate of women who reach the reproductive age can't come up to the birth replacing level. Now, the macroscopical low fertility rate has become a kind of common condition that countless families make the less reproductive decisions on the micro-level.
Western scholars find that the pursuit of a higher quality children results in less fertility rate that the families reduce the births to get more education for children. Does our country have this effect? Considering the gender structure of the micro-familial children, will the effect change? Due to the 2013 Educational Statistics Yearbook of China, more than 50% of the undergraduates and master's candidates are females. It seemingly indicates that our country has fulfilled the “gender equality” and even the “female priority” in the aspect of education. Does the “gender discrimination” of residents' educational investment not exist any more?
In order to solve the problems above, this article carries out the document analysis firstly and furthermore. It finds that the promotion of education degree caused by low birth rate and the preference for sons over daughters in the field of household educational investment aren't common. It may be implemented by specific household environment, macro-economic condition and social cultural background. Many empirical studies show that the econometrical results obtained by the micro-data based on the large sample and wide range are more scientific, whereas others obtained by the specific areas and small range are suspectable. The model which uses the sibling numbers is more precise. Some studies based on the data of our country get the similar conclusions that the fewer number of children they have, the higher educational degree their children will get. But those studies are lack of endogeny eliminating and comparison of the multiple databases. Moreover, this paper uses the theoretical model to perform a preliminary analysis. We research whether the low-fertility promotes the children's educational level base on the three micro-databases that are 2010 China Family Panel Studies (CFPS), 2013 Chinese Household Income Project Survey (CHIPS) and 2017 China Household Finance Survey (CHFS). This article makes a deep analysis to solve the endogenous problem in the method that carries out Instrumental Variable and Propensity Score Matching (PSM).
Our study finds that the low birth rate leads to the increase of children's educational degree, especially after the implement of the birth control policy, therefore we prove the “quantity-quality substitution” effect of families in China. After analyzing the individual difference, this paper finds that the promoting effect to male simples is more remarkable than to females. The more brothers can bring the “crowding-out effect” to the educational gains by the females. The difference in sibling gender composition leads to families' educational investment asymmetrically. With the birth control policy being eased, our government should carry out more related complementary policies, the most important one of which is to support policies for education, especially in the field of public educational investment. The greater public educational investment can alleviate the “dilemma” of the familial resource constraints in order to improve the educational level of all children. The empirical model of this paper that proves the increase in the girl's educational level can easily be influenced by the number of siblings, especially by the number of brothers. So we should not only reinforce the concept of the “gender equality” but also increase the household educational investment in order to reduce the phenomenon of “sexism”. Our government should pay more attentions to the female educational gains in the micro families and advocate the “gender equality” of the educational investment.

Key words: Low Fertility, Siblings Sex Composition, Educational Level, PSM