As opposed to reliability based on the classical test theory, ____ focuses on the range of item difficulty that is useful in assessing an individual's ability

James Pennebaker has demonstrated that

A) ?writing or talking about traumatic events can produce positive results. B) ?relaxation training is more effective than biofeedback to address pain. C) ?social support is critical in helping patients to cope with chronic pain. D) ?social support is not critical in helping patients cope with chronic pain.

Jenny thinks she knows what Professor Black’s study is about and so she responds in a way that she thinks will help him to support his hypothesis. How can Professor Black maximize the validity of his observations of Jenny’s behavior?

A. He can tell Jenny the true purpose of his study. B. He can keep Jenny blind to the true purpose of his study. C. He can keep Jenny and the person observing her behavior blind about the purpose of his study. D. He can cancel the study entirely. E. He shouldn’t do anything because validity is not that important.