Four Decades of Group Hypnosis Scales: What Does Item-Response Theory Tell Us About What We?ve Been Measuring?

To overcome problems with previous psychometric approaches to hypnosis scales, the authors applied full-information factor analysis, based on multidimensional item-response theory (IRT), to a 39-year sample of 11,517 records of the Harvard Group Scale of Hypnotic Susceptibility, Form A (HGSHS:A).…