During the COVID‐19 pandemic, countries applied trade restrictions to insulate their domestic markets from the world market. However, these trade policies could have amplified international market price fluctuations. This paper explores the effects of trade restrictions on international agricultural price volatility. A theoretical model is developed to quantify how trade policies amplify the initial shock. Using panel data covering 71 countries from January 2020 to July 2021, we examine empirically the effects of trade policies on world agricultural price volatility. The results show that trade distortions further induced volatility of world agricultural prices by around 22 percent during the COVID‐19 pandemic. The multiplier effects are much more substantial in agricultural exporting countries than in importing countries. Large countries like China and the US could make significant contributions to stabilizing world prices by limiting the extent of unilateral trade policy interventions.

Compared with non-myopic students, myopic students face more barriers to learning (e.g., inability to see the blackboard clearly) and socializing (e.g., being victims of teasing, social exclusion and violence), which may lead to increased stress, anxiety and frustration. The high prevalence of myopia and depression among school-age children naturally raises a question of great policy relevance: are myopic students more vulnerable to mental health problems such as depression? This paper sheds some light on this question by analyzing data from the China Education Panel Survey, a large-scale survey of China’s middle school students. Our analysis first quantifies the association between myopia and sample students’ depression status (measured by the widely adopted CES-D scale) adjusted for potential confounding factors. We then explore whether the myopia–depression relationship is mediated by wearing eyeglasses, a cost-effective means of vision correction. Based on data on 19,299 middle school students, our analysis reveals that myopic students scored 0.12 standard deviations higher on the CES-D scale than their non-myopic counterparts. The adverse effect of myopia is more severe for relatively disadvantaged students: older students (who are more likely to suffer from both myopia and depression), lower-performing students and students from poorer families. Further medication analysis shows that wearing eyeglasses suppresses the myopia–depression relationship but cannot completely offset the adverse effect of myopia.