Broadening Horizons: Integrating Quantitative and Qualitative Research

Health research usually employs quantitative, often experimental, methods to study clinical conditions and outcomes. The use of qualitative methods in this type of research is much less common. However, we contend that qualitative research , in combination with quantitative research, can play an important role generating an improved understanding of disease, health and health care. Data collected in qualitative research are usually in narrative rather than numerical form , such as the transcript of an unstructured , in-depth interview. Analysis of qualitative data organizes , summarizes and interprets these nonnumerical observations. The goal of qualitative research is the development of concepts that help clarify phenomena in natural, rather than experimental, settings, giving due emphasis to the meanings, experiences and views of all the participants being studied. For example, to understand why some members of ethnic minorities have refused tuberculosis treatment, qualitative, culturally sensitive interviews may be much more informative than standardized quantitative interviews. Both quantitative and qualitative research have weaknesses that to some degree are compensated for by the strengths of the other. Quantitative research is very well suited to establishing cause-and-effect relationships, to testing hypotheses and to determining the opinions, attitudes and practices of a large population, whereas qualitative research lends itself very well to developing hypotheses and theories and to describing processes such as decision making or communication processes. Quantitative research generates factual, reliable outcome data that are usually generalizable to some larger populations, and qualitative research produces rich, detailed and valid process data based on the participant's, rather than the investigator's, perspectives and interpretations (1). Quantitative research is usually deductive, relying on experimental and survey methods to test specific hypotheses based on general principles. It is strong in inductive reasoning, building and expanding theories concerning relationships among phenomena . In the actual practice of scientific research, theory and research interact through a never-ending cycle of deduction, induction, deduction, induction and so forth (2). By combining quantitative and qualitative methods , a degree of comprehensiveness may be achieved that neither approach , if used alone , can achieve. For example, to target populations of children who are not being immunized for common childhood infectious diseases, it is critical to quantify the existence of a low rate of immunization. However, to intervene to rectify the identified problem, it is important to explore why parents are not having their children vaccinated. Qualitative interviews are most appropriate for this purpose.