Generic health measurement: past accomplishments and a measurement paradigm for the 21st century.

Generic health surveys have been proposed for use in increasingly diverse applications and populations. This paper describes the history of generic tools in the past 30 years and suggests a more modern measurement platform for advances in the 21st century. Many generic tools lack the precision required for effective health care decision making. A meaningful goal for the next era of development of generic measures should be the generation of equiprecise measurement for generic health concepts. Equiprecise tests yield measures of equal precision at all levels of the underlying construct. Equiprecise measurement can be achieved through conjoint use of computerized-adaptive testing as the survey platform and item response theory as the measurement theory.