We present in this paper evidence about the effects and mechanisms of gender peer effects in elementary, middle, and high schools. For identification, we rely on idiosyncratic variations in gender composition across adjacent cohorts within the same schools. We find that an increase in the proportion of girls improves boys and girls' cognitive outcomes. These academic gains are mediated through lower levels of classroom disruption and violence, improved inter-student and student-teacher relationships, and lessened teachers' fatigue. We find no effect on individual behavior, which suggests that the positive effects of girls on classroom environment are mostly due to compositional change. (JEL I21, J16)

This paper presents evidence on the child-quantity/child-quality trade-off using quasi-experimental variation due to twin births and preferences for a mixed sibling-sex composition, as well as ethnic differences in the effects of these variables. Our sample includes groups with very high fertility. An innovation in our econometric approach is the juxtaposition of results from multiple instrumental variables (IV) strategies, capturing the effects of fertility over different ranges for different sorts of people. To increase precision, we develop an estimator that combines different instrument sets across partially-overlapping parity-specific sub-samples. Our results are remarkably consistent in showing no evidence of a quantity-quality trade-off.

We estimate the extent of ability peer effects and explore the mechanisms through which they operate. Using within-school variation in the proportion of low-ability students in Israeli schools, we find that the proportion of low-ability peers has a negative effect on the performance of regular students. An exploration of the underlying mechanisms show that, relative to regular students, lowability students report higher levels of satisfaction with their teachers. However, a higher proportion of low-ability students has detrimental effects on teachersÕ pedagogical practices and on the quality of inter-student and student-teacher relationships, and increases the level of violence and classroom disruptions.In this article, we study the existence, magnitude and mechanisms of peer effects on educational outcomes in middle and high schools. Specifically, we investigate whether having unusually low-achieving classmates has any effect on the educational outcomes of regular pupils and we also identify some of the mechanisms and channels through which these effects operate.Using studentsÕ exact date of birth and the rules governing school enrolment in first grade, we identify as potentially low-ability students those who were born substantially before the relevant threshold date for their cohort (ÔrepeatersÕ). 1 We show that repeaters have substantially lower academic achievements relative to both regular students and relative to any other group of students identified based on their socioeconomic background. We then assess how classroom ability composition, as measured by the proportion of repeaters in the grade, affects scholastic achievements of high school students. Lastly, we use a unique national survey administered to middle school students to identify whether peer composition affects teachersÕ pedagogical methods in the classroom, the level of disruption and violence, and the quality of inter-student and student-teacher interactions.The article makes two main contributions to the literature on peer effects. First, it identifies the effects of having low-ability peers on studentsÕ achievement using a methodology that is less susceptible to bias from potential confounders associated with peer quality and to a reflection problem. Second, it goes beyond the peer effect

Job protection and cash benefits are key elements of parental leave (PL) systems. We study how these two policy instruments affect return-to-work and medium-run labour market outcomes of mothers of newborn children.Analysing a series of major PL policy changes inAustria, we find that longer cash benefits lead to a significant delay in return-to-work, particularly so in the period that is job-protected. Prolonged parental leave absence induced by these policy changes does not appear to hurt mothers' labour market outcomes in the medium run. We build a non-stationary model of job search after childbirth to isolate the role of the two policy instruments. The model matches return-to-work and return to same employer profiles under the various factual policy configurations. Counterfactual policy simulations indicate that a system that combines cash with protection dominates other systems in generating time for care immediately after birth while maintaining mothers' medium-run labour market attachment.

This paper presents evidence on the child-quantity/child-quality trade-off using quasi-experimental variation due to twin births and preferences for a mixed sibling-sex composition, as well as ethnic differences in the effects of these variables. Our sample includes groups with very high fertility. An innovation in our econometric approach is the juxtaposition of results from multiple instrumental variables (IV) strategies, capturing the effects of fertility over different ranges for different sorts of people. To increase precision, we develop an estimator that combines different instrument sets across partially-overlapping parity-specific sub-samples. Our results are remarkably consistent in showing no evidence of a quantity-quality trade-off.