See Teacher Yuan Zhenguo's Educational Research Methods (Higher Education Press, 2000), Chapter 14, Action Research. At the beginning, it is discussed as follows: "Strictly speaking, action research is not an independent research method, but an educational research activity, which is an educational research activity in which teachers and educational administrators closely combine their own jobs and comprehensively use various effective research methods to directly promote educational improvement."

Apart from the description in the middle, Mr. Yuan Zhenguo thinks that action research is only a research activity, not strictly a research method. So in his book, this chapter is introduced as the last chapter of the book, which is placed behind the chapter of data analysis and result processing. It can be seen that Teacher Yuan did not regard it as a research method.

Back to the question, if you are writing a dissertation, you must be inclined to theoretical research and basic research. Action research is mostly for on-the-job educators (mainly teachers, principals and other frontline groups), and it is done to improve practice and tends to be applied research. So I think the inappropriate place may be here.

I am also curious to look back here today. I tried to search and found that someone had the same question as me, haha? It is best to combine several major bibliographies to study. I haven't read Pei Shuna's Introduction to Educational Research Methods, which is also an authoritative work, and so is Chen Xiangming. Let's study together!