Of course, the research of Ph.D. in economics is also limited by the academic "taste" and cannot be arbitrary, but it is much more free and independent than many other disciplines. The main reason is that the doctoral thesis of economics is basically self-made, and most of the tutors are arch-tube; This is quite different from the situation that many doctoral students in science and engineering become a screw in the boss's academic machine. However, many doctoral students in economics have to go through an extremely painful stage of self-doubt and self-denial. One of the major characteristics of economics (and many "brother" social sciences) is that it is greatly influenced by the academic atmosphere, and it is difficult to grasp and evaluate the factors such as "interesting or boring", "important or unimportant" and "feasible or unfeasible" in the research direction, which also leads to the lack of direction for doctoral students, a rookie in academic circles. I know many students who have dropped out of school. Because they are not used to the confusion caused by so much freedom, they stay at home when their work pace is "short, flat and fast".