Developing an index to measure the voluntariness of consent to research.

The goals of the current study were to expand the content domain and further validate the Coercion Assessment Scale (CAS), a measure of perceived coercion for criminally involved substance abusers being recruited into research. Unlike the few existing measures of this construct, the CAS identifies specific external sources of pressure that may influence one's decision to participate. In Phase 1, we conducted focus groups with criminal justice clients and stakeholders to expand the instrument by identifying additional sources of pressure. In Phase 2, we evaluated the expanded measure (i.e., endorsement rates, reliability, validity) in an ongoing research trial. Results identified new sources of pressure and provided evidence supporting the CAS's utility and reliability over time as well as convergent and discriminative validity.