Quality-adjusted life years, or QALYs, is a measure used to evaluate the value of medical interventions. It combines the quantity of life gained from a treatment with the quality of that life. One QALY is equivalent to one year of life in perfect health. If a treatment allows a person to live for two years with a health condition that reduces their quality of life, it might be valued at 1.5 QALYs. QALYs help healthcare providers and policymakers make informed decisions about resource allocation. By comparing the cost-effectiveness of different treatments, they can prioritize interventions that provide the greatest overall benefit to patients and society.