Visual analog scales: Do they have a role in the measurement of preferences for health states?

Visual analog scales (VASs) have long been used as a method of measuring pr eferences for health outcomes. They are easy and inexpensive to implement, can be administered quickly, and lend themselves to self-completion. Over t ime, however, disturbing questions have emerged concerning the validity of the VAS approach. This article reviews briefly the history, theory, practic e, problems, and advantages of VASs; presents some suggestions to improve t he validity of VASs; and recommends a limited but useful role for VASs in t he process of measuring preferences for health states.