See Randomization.

A randomized controlled trial (RCT) is a kind of clinical trial.  People in the study are put in the investigational or control group by chance.  People in the investigational group get the new treatment.  People in the control group get the standard treatment.  The results for both groups are compared very carefully.  Researchers compare rates of disease, death, recover, or other health outcomes for both groups.  Most scientists think that RCTs are the most reliable studies.

Randomization is when people in a clinical trial are assigned to a group by chance.   That is, the investigational group and control group are picked at random, like flipping a coin.  This means the people running the study do not decide who gets which treatment.

Rapid Cycle Change is a quality-improvement method that identifies, implements and measures changes made to improve a process or a system. At the onset, the team sets an outcome measure based on the system's goals. Improvement occurs through small, rapid PDSA (Plan, Do, Study, Act) cycles to advance practice change. This model requires targeting a specific area to change; planning changes on the basis of sound science, theory and evidence; piloting several changes with small patient groups; measuring the effects of changes; and acting according to the data. The fundamental concept of rapid-cycle improvement is that health care processes—once defined, in place and in effect—should be continually improved by instituting a constant cycle of innovations or improvements.

an example of a data set in which data are systematically collected at the hospital, state, and/or population level.  The use of registries is common in cancer-related health services research.

A measure is considered reliable when it produces the same result repeatedly when used in the same population.  A reliable measure is measuring something consistently, but not necessarily what it is supposed to be measuring.

A Report Card is an assessment of the quality of care delivered by health plans. Report cards provide information on how well a health plan treats its members, keeps them healthy and provides access to needed care. Report cards can be published by states, private health organizations, consumer groups or health plans.

Insurance companies' practice of dropping patients after they file expensive claims, on the ground that applicants misrepresented their medical history when they signed up for coverage.

A Return on Investment (ROI) is the amount of improvement in care brought about by a certain investment. ROI can also refer to the theory that if you invest in health care quality now, then the quality of care for patients will improve in the future.

Right Care is made up of the treatments that, according to evidence-based guidelines, are effective and appropriate for a given condition. Indicators used to define right care are often grouped into two categories: prevention and chronic care.