Healthcare services are a major economic activity. Measurement of their value and volume in the national accounts is complicated because patients, providers, and insurers interact in multiple ways, often in a nonmarket setting, and because healthcare services undergo significant technical change. The monetary valuation of health services in the national accounts typically relies on a producer perspective, which may differ from the value that individuals attribute to health services. However, this consumer perspective cannot be ignored when it comes to quality-adjusting measured quantities of health services. Along with quality adjustment, the question of how to define and measure units of health services output needs answering. Methods vary among countries, some relying on volume measures of inputs while others gauge volume measures of treatment of diseases.