Qualitative research methods play a crucial role in complementing the quantitative approach in HCI by providing in-depth insights into user experiences, motivations, and perceptions that quantitative data alone may not capture. Qualitative methods such as interviews, observations, and think-aloud protocols can help researchers understand the context, emotions, and subjective aspects of user interactions with technology. By combining qualitative and quantitative approaches, researchers can gain a comprehensive understanding of user behavior and preferences. Triangulation, a method that involves integrating findings from both qualitative and quantitative data sources, can enhance the validity and reliability of research outcomes. Researchers can use mixed-methods designs to leverage the strengths of each approach and provide a more holistic view of the research problem.