The qualitative research approach "aims to understand the social world through the viewpoint of respondents, detailed descriptions of cognitive and symbolic actions and the richness of meaning associated with observable behaviour," according to researcher Margaret Myers. Rather than a focus on numerical data that seeks to quantify and define norms, qualitative research describes trends, tolerates nuance and complexity, accounts for context, and searches for general patterns. However, this approach also reduces the barriers between researcher and subject--a situation which some feel renders impossible the goal of objectivity.
Qualitative research is often criticised for its lack of generalizabiltiy. The Colorado State University Writing Center defines generalizability as "the extension of research findings and conclusions from a study conducted on a sample population to the population at large." Because the qualitative approach tends to focus on the context and details that are unique to each research situation and usually involves only a small data set, results can be relative to the research setting and subjects. Qualitative research methods generally include in-depth interviews, fieldwork and participant observation: all methods that focus on a small group of subjects. However, proponents of the qualitative method may argue that generalizability should not always be a primary goal or value. Some studies may have little need of generalisation. An in-depth or locally-applicable study could actually have more value than a large, impersonal study in certain situations. According to Myers, "small qualitative studies can gain a more personal understanding of the phenomenon and the results can potentially contribute valuable knowledge to the community." Qualitative methods, such as case studies, can be especially valuable to field such as political science, social work and education.
In order to be considered valid and credible, research must be replicable. In fact, in the world of empirical research, many feel that if a result cannot be replicated, the conclusion of a study cannot be valid. However, due to a tendency to focus on particular context and personal interpretation, qualitative research can be difficult to replicate. According to Princeton University's Andrew Moravcsik, "once theories and cases are selected, case study analyses tend to proceed almost entirely without explicit methodological rules--particularly with regard to the treatment of evidence. The selection, citation, and presentation of sources remain undisciplined and opaque." The lack of formalised methodology makes valid study replication very difficult.
Another common criticism of qualitative research is lack of objectivity. Because the researcher is usually an active participant in qualitative research--especially when engaged in methodologies such as interviews or participant observation--the researcher is not simply a detached, impartial recorder of data, as in quantitative research. Thus, qualitative research is considered "more easily influenced by the researcher's personal biases and idiosyncrasies," according to the University of South Alabama. Proponents of qualitative research argue that an emic, or insider's perspective, is helpful and even necessary when studying some types of subject matter.