Error due to systematic differences in characteristics between those who are selected for a study and those who are not.

Self-Management is the ability of individuals to have the necessary knowledge, attitudes and skills to manage their health problems or disorders on a day-to-day basis. It is a skill that enables individuals, and their families, to make improved use of existing health services, as well as make choices surrounding health care providers, medication, diet, exercise and other lifestyle issues that protect or damage health.

A Sentinel Event is any unexpected event in a health care setting that causes death or serious injury to a patient and is not related to the natural course of the patient's illness.

A government-run healthcare-delivery system for all citizens, paid for by tax dollars.  Both Britain and Canada have single-payer.

Specialty Care is health care focused on improving the well being of certain specialized categories of health, as opposed to general and overall health and well-being. To improve the quality of health care available to consumers and patients, providers must improve the quality and availability of primary and specialty care.

The standard of care is a yardstick for measuring the level of health care.  Standards of care may be used to compare what a particular health plan offers with the generally accepted level of care.  The standard of care may be developed by a group of specialists or by advocates for people with special needs.  Good standards of care are based on medical evidence.

A study's results are statistically significant when the results most likely did not occur simply by chance.  Researchers apply a mathematical formula to the data from the study to find its statistical significance.

A statistical technique or method is a way of collecting and looking at numbers.  Researchers use statistical techniques to help make sense out of numbers they collect in a study.

Supply-Sensitive Care includes excess procedures, hospital admissions and doctor visits driven by the supply of doctors and hospital resources, rather than by need.

Survey methodology is the set of ways used to ensure that valid and reliable information can be obtained directly from individuals.  Methods include paper and pencil, web (or other electronic means), phone, and mail.

A systematic review is an efficient scientific technique used to identify and summarize evidence on the effectiveness of interventions.  Systematic reviews are considered the highest level of evidence because they allow the generalizability and consistency of research findings to be assessed and data inconsistencies to be explored.  Most systematic reviews are based on a quantitative meta-analysis.  The best source for systematic reviews is the Cochrane Collaboration.