The single most important function of UX research is to establish and maintain understanding. What is the goal? Are we asking the right questions in service of the goal? Do we understand our intended audience? Are we missing part of our audience? Are we missing anything?
I practice human-centered, mixed method user experience research. This involves first understanding the goal and constraints of the project, and then turning that focus to understanding the needs of those who are intended to use or benefit from the project. Qualitative and quantitative investigations involving in-depth user interviews, surveys and data analysis are key to this level of understanding.