A conjoint measurement analysis of clinical predictions.

A lack of impressive theories in clinical psychology has been attributed to an excessive reliance on significance testing. Conjoint measurement is a worthwhile alternative to significance testing. Conjoint measurement determines whether data obey the ordinal properties of a model that contains main effect terms, interaction terms, or a combination of the two. Unlike hypothesis testing, with conjoint measurement an increase in statistical power leads to a greater risk of refuting a theory. In this study, conjoint measurement was used to describe how systems-oriented therapists predict the occurrence of suicide. Although the systems approach emphasizes the interaction between an individual and a system, all 10 clinicians were described by an additive model.