Studies have identified negative effects of cortisol, a stress hormone, on academic performance. Because natural disasters induce community-wide stress, students who experience natural disasters may subsequently perform worse academically. Our study is the first to examine the immediate effects of close exposure to a natural disaster on academic performance. We examine the impact of the 2017 Pohang earthquake in South Korea on college entrance exam scores. The 5.4 magnitude quake occurred one day before the scheduled nationwide college entrance exam date, necessitating its postponement for one week. Several aftershocks occurred during that postponement period. We find that the earthquake decreased the reading test scores of students in the Pohang area by 0.05 standard deviation but had no effect on math test scores. The reading test was administered earlier in the day than the math test, so these findings suggest that students taking exams in post-traumatic situations might be able to perform better after a warm-up testing period. Finally, male students suffered the largest adverse impacts on their reading test scores, with serious implications given the high-stakes nature of the exams.

This study examines the hypothesis that having an older sister causes one to perform relatively better at reading. For the analysis, a cross-subject analysis is conducted to examine a student's relative reading test score (reading test score minus math test score) based on older sibling gender. We found that a student's relative reading test score is larger when the student has an older sister than when he or she has an older brother. Further analyses show that although conversation frequency does not vary based on older sibling gender, siblings are more likely to talk about studying, career paths, or school life when an older sibling is a sister than when an older sibling is a brother.