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Abstract

Exploiting data from Ghanaian schools’ eighth grade students collected in 2011, we estimate the causal effects of school bullying on academic achievement and gender-based mitigating approaches by using propensity score matching (PSM) and doubly robust (DR) estimator approach. We find that students victimized by bullying score at least 0.22 standard deviation lower than their peers in a standardized mathematics examination. Meanwhile, we document that the effect of bullying is significantly attenuated in the presence of female teachers in the classroom. These results hold through a set of robustness checks including placebo regressions and matching quality test. We explain the results through gender difference in teaching paradigm and conclude that a feminine management approach in class is required to reduce the effect of bullying.

Abstract

In this article, we investigate two types of asymmetries, that is, the asymmetry of conditional volatility and the asymmetry of tail dependence in the crude oil markets. We employ the two different sample datasets in which each dataset covers the time period of stable and unstable oil prices, individually. A variety of different copulas and three asymmetric GARCH regression models are used in odrder to capture the two types of asymmetries. In particular, we extend the TBL-GARCH model proposed by Choi et. al. (2012) to the asymmetric GARCH regression type model. The findings from the two different apporaches are congruent, in that there is no asymmetry of tail dependence and no asymmetric conditional volatility in crude oil returns over the two different sample periods. Our study reconfirms the findings of Aboura and Wagner (2016) by showing that asymmetric conditional volatility relates to asymmetric tail dependence.