Health care quality is a level of value provided by any health care resources as determined by some measurement. As with quality in other fields, it is an assessment of whether something is good enough and whether it is suitable for its purpose. The goal of health care is to provide medical resources of high quality to all who need them; that is, to ensure good quality of life, to cure illnesses when possible, to extend life expectancy, and so on. Researchers use many different quality measures to attempt to determine health care quality, including counts of a therapy's reduction or lessening of diseases identified by medical diagnosis, a decrease in the number of risk factors which people have following preventive care, or a survey of health indicators in a population who are accessing certain kinds of care.