The main purpose behind the writing of the fourth chapter of your dissertation or the research methodology chapter is to enable an experienced investigator to be able to replicate your research work. Research should, however, also be structured appropriately and such that it demonstrates all the major parts of the dissertation. These parts of the dissertation should go toward addressing the question of your research work.
Introduction
Chapter four or the research methodology chapter has the information that is needed by its reader to understand all the scientific methods and steps that have been used by the researcher in order to learn about the reliability and the validity of the study. You should also consider starting your fourth chapter with a brief introduction since it would tell people the purpose of this chapter. You need not even apply much imagination. You should not write more than three paragraphs.
Appropriateness
While some academic institutions make this chapter compulsory, the others make it voluntary. In this section, you should specify whether the research is quasi-experimental, experimental, correlational, causal-comparative, qualitative, quantitative or another type of research. Be as specific as possible. You should defend this kind of approach by comparing the method you have used with the other methods. In other words, you should deny the other methods and justify why you had never used them.
Research design
Remember the purpose behind writing this chapter, the theoretical framework of your study, the research question, etc. You should be able to convince your reader that the approach you have chosen in order to write this chapter is appropriate. Include a description of the research design including whether you have used the qualitative, the quantitative method or any other method. Also, make sure you include a description of the independent as well as the dependent variables.