Q: What type of methods should I use in security studies dealing with ethnic conflicts?

Your question is not very clear. You have not provided the details of your proposed study in the description section either. It is, in fact, difficult for someone else to suggest methods for a study that you are conducting. As a researcher, you will first have to get clarity on what your study objectives are. Based on these, will have to come up with study design and methods that will be feasible and will help you achieve the objectives.

I cannot really tell you what methods to use without understanding your work. This is something you will have to decide for yourself. Another thing that you can do is to read up existing studies on similar topics. This will give you an understanding of how such studies are usually designed.  

Related reading:

• Types of qualitative research methods
• 7 Biases to avoid in qualitative research