The effect on reliability of adding a separate written assessment component to an objective structured clinical examination

PURPOSE: To determine the effect on test reliability when a separate written assessment component is added to an objective structured clinical examination (OSCE). METHOD: Volunteers (n=38) from Maastricht Medical School were recruited to take a skills-related knowledge test in addition to their regular end-of-year OSCE. The OSCE scores of these volunteers did not differ from those of the other students of their class. Multivariate generalizability theory was used to investigate the combined reliability of the two test formats as well as their respective contributions to overall reliability. RESULTS: Combining the two formats has an added value. The loss of reliability due to the use of fewer stations in the OSCE can be fully compensated by lengthening the written test component. CONCLUSION: From the perspective of test reliability, it is possible to economize on the resources needed for performance-based assessment by adding a separate written test component.