Purposeful assessment techniques (PAT) applied to an OSCE-based measurement of competencies in a pediatric dentistry curriculum.

Careful measurements of knowledge, attitude, and psychomotor and communication skills are necessary components of testing in a competency-based approach to education in dentistry. In an effort to address these requirements, Baylor College of Dentistry (BCD), Dallas, Texas, has applied Purposeful Assessment Techniques (PAT) to the Objective Structured Clinical Examination (OSCE) currently in use. PAT are those techniques that allow one to work toward development of linear measurement scales that are "person-free" and "item-free." Person-free measurement means that useful data are produced regardless of the group being measured and item-free measurement means that it does not matter which mix of items is completed over the course of an assessment. The Rasch probabilistic model and a guiding definition of Objective Measurement were used in an effort to implement PAT for the BCD OSCE. A Rasch analysis of a BCD-administered OSCE produced an item map that demonstrated the range of difficulty of items by student performance. This item map can be used to determine which items can be repeated on subsequent tests to allow for linear measurement of students' progression through the curriculum. The movement toward PAT described in this paper demonstrates how careful and evolving measurement in dental education can be of great benefit to faculty, staff, students, and the public.