The customer purchase decision process

Write a thesis on the customer purchase decision process in the German washing machine market. For this I need a literature review on the topic of market research. Since I want to do a qualitative (interview) and quantitative (survey) with a gamification part the chapter must have the following subchapters at least.

1. Historical introduction to market research
2. Qualitative research (focus on interviews)
   a. Overview
   b. Types
   c. Evaluation
3. Q Methodology
4. Qualitative research (focus on surveys)
   a. Overview
   b. Types
   c. Evaluation
5. Gamification as a part of an survey
6. Decision Trees