Case Control Study - The comparison of individuals with a certain illness to similar healthy individuals, matched by age, sex or other factors in order to define risk factors for the illness.

Clinical Trials - Studies which compare a well-known, or standard, treatment with a newly developed treatment. Clinical trials are usually done in three phases. Phase I tests the safety of the treatment on a small number of patients. Phase II assesses the effectiveness of the treatment and usually involves a larger group of people. Phase III provides in-depth information about the effectiveness and safety, by comparing experimental treatment with the standard protocol. Phase III trials usually involve several thousand patients nationwide. Randomized clinical trials, considered the "gold standard" of scientific research, involve study participants who are randomly assigned to different treatment groups and then compared.

Double-Blind - Clinical trial in which participants do not know what treatment they are receiving. The doctors and nurses treating them don't know either. Researchers keep this information secret until each patient's health status is known, usually after at least a year or more of treatments.

Peer Review - Evaluation by scientists working in the same field in which the research was done, in order to assess the reliability of the results and conclusions.

Prospective Study - Studies which evaluate participants at a specific timepoint, and undertake some intervention (a drug is given or a risk factor is removed, for example), then examine them later to see the effect of that intervention.

Retrospective Study - Studies which look back at the development or course of disease in a group of people, examining how their lifestyle or other risk factors may have affected whether they developed the disease or not, or how treatment may have affected the severity or progression of the disease.