Which of the following best describes qualitative research?

Qualitative research is best characterized by its focus on subjective data to gain insights into human behavior, experiences, and emotions. This approach typically uses methods such as interviews, focus groups, or observations, which allow researchers to explore the complexities of social phenomena and understand the reasoning behind individuals' actions and thoughts.

By emphasizing the depth of understanding rather than numerical data, qualitative research seeks to provide a rich, detailed picture of participants' perspectives. This method is particularly valuable in fields where understanding context, meanings, and motivations is crucial, such as psychology, sociology, and market research.

The other options refer to methodologies that do not align with the principles of qualitative research. A numerical approach focuses on quantifiable data analysis, which is characteristic of quantitative research. A method focused solely on measurable outcomes aligns with experimental or quantitative methodologies that prioritize statistical analysis. Lastly, a study design requiring controlled experiments suggests a structured approach used in hypothesis testing, common in quantitative research but not in qualitative inquiry.