Double-blind studies are useful in medical research.
Research design largely depends upon the questions that researchers are trying to answer. Once a researcher determines the central themes of her study, she can choose a design that will most effectively answer those questions. Of course, other factors are important when considering research study design, including availability of subjects, location of resources, and difficulty of recording and maintaining data. The two primary types of research studies are quantitative and qualitative.
Quantitative Research
Quantitative research studies, as the name suggests, deal with quantities or numerical data. These studies involve the gathering of measurable data and statistical analysis of that data. Quantitative research is used in almost all disciplines, including education, medicine and social sciences. These studies usually seek to prove or disprove the hypotheses or research questions.
Qualitative Research
Qualitative research studies are more observational. The data gathered in these studies is verbal rather than numerical. Qualitative studies often lead to more questions than answers, and may even be used as a forerunner to quantitative research. Qualitative data can be used to assist researchers in formulating quantifiable questions and studies.
Descriptive Designs
Descriptive studies are particularly useful in psychology and social sciences. Case studies are a type of descriptive study used to analyze an individual or population in depth. Researchers often use surveys and questionnaires in descriptive studies to determine opinions or reactions. Observation of the subject in his natural environment or in authentic situations is another type of descriptive research. While descriptive studies can yield useful behavioral information, they cannot be used to prove or disprove any hypotheses.
Correlational Studies
Correlational research is common practice in medicine, psychology and social science. Researchers use observational studies to compare variables that they cannot ethically manipulate. For example, in a study comparing the health of smokers and non-smokers, the scientist cannot ethically choose who will smoke. Longitudinal studies are observational studies used to analyze long-term effects of a medicine, behavior or treatment. A cohort study is a longitudinal study of a specific group of individuals, usually sharing a particular trait or set of traits, over a period of time. Cross-sectional studies focus on a specific population. One example of a cross-sectional study would be the incidence of lung cancer in women of a certain age or ethnic group. Correlational studies are very useful for observing and even measuring data when the variables are beyond the scientists' control. However, these studies are limited in terms of determining direct cause and effect, due to the vast amount of outside factors influencing the subjects.
Experimental Designs
Experimental studies are considered pure science because the data is quantifiable, can be statistically analyzed, and can verify or refute a specific hypothesis. True experimental design requires that subjects be assigned randomly to experimental or control groups. If no control group is possible, the study cannot be a true experimental design. In general, only a single variable can be altered and assessed in the study. In a blind experiment, the subjects do not know if they are in the control group or the experimental group. In a double-blind study, neither the researchers nor the subjects know who is assigned to which group. Experimental studies are useful in the fields of geology, physics and chemistry. The major disadvantage of true experimental design is its lack of real-world application.
Quasi-Experimental Studies
Quasi-experimental design is used extensively in studies of psychology, education and other social sciences. These studies do not involve random assignment in control or experimental groups. Information from case studies and survey studies may be used to generate quasi-experimental research. The data is measured using the same statistical analysis as experimental studies, but the researcher has little or no control over variables. Field experiments and twin studies are examples of quasi-experimental studies used in the fields of biological and physical science.
Tags: experimental design, research studies, social sciences, studies used, cannot ethically
