A study involving three individuals (ages 13-20) with developmental disabilities and problem behaviors examined the influential role that unanticipated idiosyncratic stimulus variables play in affecting the outcome of a functional analysis. Guidelines are discussed concerning when to suspect that idiosyncratic stimuli might be acting to influence…

Five criteria are proposed for evaluating performance in research studies: the directness of sampling, the responsiveness of the target, the reliability of the observers, the frequent assessment of the target during the intervention period, and the critical nature of the target. A case study illustrates effectiveness of the criteria. (Author/CR)