一旦确定了研究问题，就必须在确定研究方法以及如何操作该方法的过程中选择

一旦确定了研究问题，就必须在确定研究方法以及如何操作该方法的过程中选择分析单位。

Results (English) 1:

Once the research question is determined, the analysis unit must be selected in the process of determining the research method and how to operate the method.

Results (English) 2:

Once the research problem is determined, the analysis unit must be selected in the process of determining the research method and how to operate the method.

Results (English) 3:

Once a research problem has been identified, the analytical unit must be selected in determining the research method and how to operate it.