Construction and validation of the Assessment of Quality of Life (AQoL) mark II instrument

The AQoL program explored methodological innovations in MAU instrument construction using psychometric methods to develop a descriptive system based upon handicap and the use of a multi level descriptive system in which latent dimension variables are constructed from individual items and which, in turn, create the latent AQoL variable. The paper reports chief results and discusses problems associated with negative utilities, spontaneous versus deliberative weights, framing effect bias. New validation procedures are used to test for the existence of a ‘strong interval property’, the defining characteristic of the QALY. One external validation test of the strong interval property is reported.