Clinical research is the scientific process to answer research questions related to health and disease through clinical studies. A clinical study involves human volunteers (also called participants) and is intended to advance medical knowledge and practice. There are two main types of clinical studies: clinical trials (also called interventional studies) and observational studies. A clinical trial involves testing interventions such as medical products, medications, or procedures, whereas an observational study observes participants over a given time period. More information on clinical studies is available here.
Because medicines must be rigorously tested and participants closely monitored, it usually takes about 10 years for a new treatment to get approved. Finding enough participants -- from all backgrounds -- remains one of the greatest research challenges.
Randomized - In many studies, participants are randomly sorted into different groups. This allows researchers to observe the effects of a new treatment against a control group, which does not receive the treatment.
Double blind - In double blind studies, participants and investigators don't know who is receiving an experimental treatment. This helps reduce bias due to placebo effect (a phenomenon where people experience benefit from belief that they are receiving a treatment, which can't be attributed to the properties of the treatment itself).
Investigational - An investigational treatment has not yet received approval from the FDA.
Intervention - A health 'intervention' refers to any activity undertaken with the goal of improving human health. This includes interventions that aim to prevent disease, cure or reduce the severity of a disease, or restore function.