"Randomized experiments are the gold standard for causal inference, but they are not always feasible."

The novel is a form of exploration, a way of understanding the world and our place in it.

【解释】仁慈的人爱人，有礼貌的人尊敬人，爱别人的人，别人也会爱他；尊敬别人的人，别人也会尊敬他。