These are some of the different types of research but note that people may categorize or define research in other ways. Types are not mutually exclusive and may overlap or be used in combination with each other.
Basic scientists seek answers to fundamental questions in the biology or pathogenesis of a phenomenon, process or disease. Basic science research provides the broad base of knowledge that underlies and is necessary for developing solutions to recognized medical problems. It is often conducted in controlled, laboratory settings. It may be undertaken without looking for long-term benefits other than the advancement of knowledge or to make discoveries in specified areas that will have applied value.
Clinical research is often defined as research conducted with human subjects and which utilizes both a randomized selection process and a control group. However, it actually includes any research that involves interaction with human subjects in any way and is designed to change human behavior or outcomes. It can be conducted in a variety of settings, not just in a controlled laboratory. There are many different types of clinical research.
Clinical trials are designed to determine whether new or current interventions are both safe and effective for changing outcomes in humans. They use existing knowledge gained from basic research or practical experience for the purpose of creating new or improved products, processes, or practices. There are different types of clinical trials, although they all generally utilize randomized selection and a control group (RCT). Clinical trials are conducted in four phases, which are:
In Phase I trials, researchers test a new drug or treatment in a small group of people (20-80) for the first time to evaluate its safety, determine a safe dosage range, and identify side effects.
In Phase II trials, the study drug or treatment is given to a larger group of people (100-300) to see if it is effective and to further evaluate its safety.
In Phase III trials, the study drug or treatment is given to large groups of people (1,000-3,000) to confirm its effectiveness, monitor side effects, compare it to commonly used treatments, and collect information that will allow the drug or treatment to be used safely.
In Phase IV trials, post-marketing studies delineate additional information including the drug's risks, benefits, and optimal use.
More in-depth information on clinical trials can be found at the following websites:
Epidemiology is the study of the distribution and determinants of health-related states, disease, and events in populations and the application of this study to the control of health problems. It answers questions about who gets diseases, why, and determinants of risk. It focuses on groups of people rather than individuals, and studies those who are healthy as well as those who are sick in order to determine crucial differences between the two groups.
Health services research identifies healthcare needs and studies the provision and use of health services to meet these needs. It is a multi-disciplinary field of inquiry, both basic and applied, that examines access, utilization patterns, costs, patient and provider relationships, social and behavioral epidemiology, quality, delivery, organization, financing and outcomes of health care services. It is designed to produce new knowledge about the structure, processes and effects of health services for individuals, employees, and employers.
Policy analysis refers to research on a fundamental social problem and its related public policies. Analysts are interested in the process by which policies are adopted as well as their effects and usually provide policymakers with briefings and pragmatic, action-oriented recommendations.
A Process Evaluation assesses the quality of the implementation of a project. An Outcome Evaluation assesses how well a project worked.
Survey research is a broad area of research in which people are asked to answer questions, either through standardized questionnaires, in-depth interviews, or focus groups. Surveys are generally administered to a scientifically selected sample, although sometimes they are taken from an entire population, as in the case of the decennial U.S. census. Surveys are used to ascertain beliefs, attitudes, opinions, behaviors, needs, abilities, social status, and nearly every other aspect of peoples' lives. Data collected through surveys are used to describe individuals, estimate population parameters, and discern relationships between what people think, how they act, and the circumstances in which they live.
Analysis of Secondary Data
Secondary data analyses use data that have already been collected; that the researcher was not responsible for collecting or it was collected for a different problem than the one currently under analysis. Secondary data may be available which are entirely appropriate and wholly adequate to draw conclusions and answer a research question. Sometimes primary data collection is not necessary. Secondary data analyses can be cheaper, less time-consuming, and more accurate than collecting primary data.