The study looked at how education and skills affect a country's economic growth. They used three different ways to measure human capital: the level of education, test scores, and a combined index. They found that both physical capital (like buildings and machines) and human capital are important for economic growth. The most significant factor was the combined human capital index, which includes both quantity and quality of education. This means that having well-educated workers who are productive is crucial for a country's economy to grow.