The effect of peer socioeconomic status on student achievement: a meta-analysis

Previous studies on the effects on students' test scores of their peers' socioeconomic status (SES) reported varying results. A meta-regression analysis including 30 studies on the topic shows that the compositional effect that researchers find is strongly related to how they measure SES and to their model choice. If they measure SES dichotomously (e.g. free lunch eligibility) or include several average SES-variables in one model, they find smaller effects than when using a composite that captures several SES-dimensions. Composition measured at cohort/school level is associated with smaller effects than composition measured at class level. Researchers estimating compositional effects without controlling for prior achievement or not taking into account the potential for omitted variables bias, risk overestimating the effect. Correcting for a large set of not well thought-over covariates may lead to an underestimation of the compositional effect, by artificially explaining away the effect. Little evidence was found that effect sizes differ with sample characteristics such as test type (language vs. math) and country. Estimates for a hypothetical study, making a number of "ideal" choices, suggest that peer SES may be an important determinant of academic achievement.

Gender peer effects in university: Evidence from a randomized experiment

Recent studies for primary and secondary education find positive effects of the share of girls in the classroom on achievement of boys and girls. This study examines whether these results can be extrapolated to post-secondary education. We conduct an experiment in which the shares of girls in workgroups for first year students in economics and business are manipulated and students are randomly assigned to these groups. Boys tend to postpone their dropout decision when surrounded by more girls, and there is also a modest reduction in early absenteeism. On the other hand, boys perform worse on courses with high math content when assigned to a group with many girls. Overall, however, we fail to find substantial gender peer effects on achievement. This in spite of the fact that students in groups with many girls help each other more often and study together more often.Field experiment, Peer effects, University students

Peer Ethnicity and Achievement: a Meta-analysis Into the Compositional Effect

This study reports a meta-analysis on the effects of ethnic minority share in school on achievement test scores. Best evidence from the studies that have appeared thus far on this topic shows that these compositional effects appear small in general, but may be larger when the ethnic minority group is African Americans in the USA, than when the minority group consists of immigrants. A high share of students from an ethnic minority group seems to affect the achievement from students belonging to the same ethnic group more, than the achievement of students belonging to the ethnic majority or to other ethnic minority groups. Effects of the share of immigrants on test scores of ethnic majority students even seem to be close to zero. Several robustness checks confirm our results. The review concludes with a discussion of implications for research and policy practice.academic achievement, meta-analysis, racial composition, school segregation, ethnic groups

Saving Lives at Birth:The Impact of Home Births on Infant Outcomes

Abstract: Many developed countries have recently experienced sharp increases in home birth rates. This paper investigates the impact of home births on the health of low-risk newborns using data from the Netherlands, the only developed country where home births are widespread. To account for endogeneity in location of birth, we exploit the exogenous variation in distance from a mother’s residence to the closest hospital. We find that giving birth in a hospital leads to substantial reductions in newborn mortality. We provide suggestive evidence that proximity to medical technologies may be an important channel contributing to these health gains.

Lymphoid Microenvironments in the Thymus and Lymph Node

The three-dimensional architecture of the thymus and mesenteric lymph node reveals several different stromal cell types important in the development and function of T cells. In the thymic cortex, T cells proliferate and differentiate in a meshwork of epithelial-reticular cells. They then migrate towards the medulla where they may interact with interdigitating cells. T cells migrate from the thymus through perivascular spaces, surrounding large vessels at the cortico-medullary boundary. In this area also large thymic cystic cavities are found, their function remains at present unclear. Mature selected T cells leave the thymus most probably by the venous bloodstream, to enter peripheral lymph nodes. Upon entering the lymph node they cross the wall of high endothelial venules. On the other hand, lymph enters the node by afferent lymphatics draining into various types of sinuses. Here, macrophages are strategically located to phagocytose and process antigen. These cells then expose antigen to T cells and B cells within the lymph node parenchyma, thus creating a microenvironment for the onset of an immune response. The various microenvironments important in T cell development and T cell function are shown in this paper using scanning electron microscopy as a dissecting tool. We discuss our morphological findings in the light of recent data on the physiology of T cell differentiation and function

The Value of Early Tumor Size Response to Chemotherapy in Pediatric Rhabdomyosarcoma

Rhabdomyosarcoma is the most common soft tissue sarcoma in childhood. Results of clinical trials, with three-year event-free and overall survival as primary outcomes, often take 7 to 10 years. Identification of an early surrogate biomarker, predictive for survival, is therefore crucial. We conducted a systematic review to define the prognostic value of early tumor size response in children with IRSG group III rhabdomyosarcoma. The search included MEDLINE/EMBASE from inception to 18 November 2020. In total, six studies were included, describing 2010 patients, and assessed by the Quality in Prognosis Studies (QUIPS) instrument. Four studies found no prognostic value for tumor size response, whereas two studies reported a prognostic effect. In these two studies, the survival rate of patients with progressive disease was not separately analyzed from patients with stable disease, potentially explaining the difference in study outcome. In conclusion, our findings support that early progression of disease is associated with poorer survival, justifying adaptation of therapy. However, in patients with non-progressive disease, there is no evidence that the degree of response is a prognostic marker for survival. Because the vast majority of patients do not have progressive disease, early tumor size response should be reconsidered for assessment of treatment efficacy. Therefore, at present, early surrogate biomarkers for survival are still lacking