This case is an example of using quantitative research on democracies, and it is based on my PhD study in political science. In the study, I used a comparative method, through a large-n, outcome-centric research design, to examine which factors affect the varying levels of the quality of democracy in the stable democracies around the world. This case study illustrates how a researcher can develop their research agenda from identifying the research subject to formulating the research question for the study. In the case, I describe different research steps that were used in my PhD study, such as how the research design was developed, how the operationalization of the concept quality of democracy was performed, how the theoretical model for explaining the variation in the quality of democracy was developed, and how the empirical analyses by using statistical analysis were performed. During the research journey, there were also several methodological challenges to handle, and in this case study, I also describe and comment on how I handled these challenges. As a pedagogical tool, the aim of this case is to be helpful in improving future research that uses a large-n research design and analyzes the data using statistical analysis.