Setting and validating the pass/fail score for the NBDHE.

PURPOSE: This report describes the overall process used for setting the pass/fail score for the National Board Dental Hygiene Examination (NBDHE). METHODS: The Objective Standard Setting (OSS) method was used for setting the pass/fail score for the NBDHE. The OSS method requires a panel of experts to determine the criterion items and proportion of these items that minimally competent candidates would answer correctly, the percentage of mastery and the confidence level of the error band. A panel of 11 experts was selected by the Joint Commission on National Dental Examinations (Joint Commission). Panel members represented geographic distribution across the U.S. and had the following characteristics: full-time dental hygiene practitioners with experience in areas of preventive, periodontal, geriatric and special needs care, and full-time dental hygiene educators with experience in areas of scientific basis for dental hygiene practice, provision of clinical dental hygiene services and community health/research principles. Utilizing the expert panel's judgments, the pass/fail score was set and then the score scale was established using the Rasch measurement model. RESULTS: Statistical and psychometric analysis shows the actual failure rate and the OSS failure rate are reasonably consistent (2.4% vs. 2.8%). The analysis also showed the lowest error of measurement, an index of the precision at the pass/fail score point and that the highest reliability (0.97) are achieved at the pass/fail score point. CONCLUSION: The pass/fail score is a valid guide for making decisions about candidates for dental hygiene licensure. This new standard was reviewed and approved by the Joint Commission and was implemented beginning in 2011.

Constructing licensure exams: a reliability study of case-based questions on the National Board Dental Hygiene Examination.

Patient cases with associated questions are a method for increasing the clinical relevance of licensure exams. This study used generalizability theory to assess changes in score reliability when the number of questions per case varied in the National Board Dental Hygiene Examination (NBDHE). The experimental design maintained the same total number of case-based items, while varying the number of cases and items within cases to assess changes in score reliability. Using generalizability theory, the amounts of error variance within cases and between cases on the NBDHE were assessed. Impact on score reliability (generalizability) was computed. The data were from the responses of 4,528 candidates who took the paper-pencil version of the NBDHE in spring 2009. Results showed that the minimum value of generalizability occurred when fourteen cases with ten items each were used in the examination. The maximum value of generalizability occurred when fifty cases with three items each were used in the examination. The research findings support the development of more cases with fewer items per case on the NBDHE in order to enhance test score reliability and validity. Practical constraints should be considered if more cases with fewer items per case are developed for future examinations.