The study used data from a 2013 survey of 6th grade public school students in Recife, Brazil to investigate the impact of bullying on math scores. The researchers employed propensity score matching and other econometric techniques to account for potential biases. The key findings were that bullying had a significant negative effect on math performance, and that social-emotional skills like emotional stability could help students cope with bullying. The authors recommend that anti-bullying programs consider developing students' non-cognitive skills. Explain this in simpler terms