Qualitative research involves the use of observational methods that often result in subjective responses, such as surveys and focus groups. Quantitative research forms a structured hypothesis and measures results numerically. While each type of research has its disadvantages, some researchers feel that quantitative research is more reliable, while others feel that both methods need to be used to gain accurate findings.

Bias in Qualitative Research

One of the primary disadvantages of qualitative research is that it often contains researcher and respondent bias. Since the researcher is the one who designs the surveys, questionnaires and focus group questions, he may administer questions that elicit a certain type of response. He may unknowingly design the questions in such a way that the responses end up supporting the researcher's intended conclusion. In addition, the participants chosen for the study might not be credible or an adequate representation of the general population, or they might have direct ties to the researcher.

Qualitative Research Data is Subjective

Another main disadvantage of qualitative research is that the responses are often subjective and open to interpretation. A researcher might find it difficult to make respondents feel comfortable enough to fully disclose their true opinions and feelings. Respondents may answer in a way that they think will please the researcher or adhere to socially acceptable standards. When collecting and interpreting the data from a qualitative research study, the researcher may make interpretations that fit with her intended conclusion. She may also have difficulty analyzing and interpreting the findings accurately.

Quantitative Research Lacks Insight

While quantitative research methods collect data within a certain set of parameters and produce exact numerical results, the data does not reveal causation. It often reflects what is happening, but not why it may be happening. For some types of study, this might produce significant holes that could only be filled by qualitative methods. For example, a study that shows that autism is on the rise in young children reflects the percentage increases and the amount of of new diagnoses, but leaves the door wide open as to why it might be occurring.

Only Known Issues are Measured by Quantitative Research

One of the disadvantages of quantitative research is that it requires the researcher to form a hypothesis prior to conducting any tests. The actual test results might bring up new issues or findings that end up being discarded since they don't fit within the parameters of the hypothesis. In addition, issues that were unknown prior to the test may be overlooked. Researchers make the hypothesis based on assumptions about the conditions that they will test, which might cause them to interpret the test findings incorrectly.