The beauty of instrumental variables is that they allow us to see the world in a new light.
负责任的林业不是限制进步,而是重新定义进步的含义。
Sustainability is not just about planting trees; it's about planting the right trees in the right places for the right reasons.
I've never been interested in being average.
实证研究中最重要的是要清楚你想要回答的问题。