In this section, you present the ideas that you want to test in the empirical part of your research. The best way to develop your theory section depends on the availability of data. If you must work with a given dataset, the best way to go forward is to look at the variables in your data, and draw a causal model including the variables that are at the heart of your research. If you can collect your data yourself, e.g. by conducting an experiment, a survey, or interviews, the best way to go forward is to read a recent literature review on your research problem and work from there. If there is no literature review available on your research problem, you will need to write that review yourself. Paragraph 3.3. explains how you can do that.