When enough is enough: a conceptual basis for fair and defensible practice performance assessment.
INTRODUCTION: An essential element of practice performance assessment involves combining the results of various procedures in order to see the whole picture. This must be derived from both objective and subjective assessment, as well as a combination of quantitative and qualitative assessment procedures. Because of the severe consequences an assessment of practice performance may have, it is essential that the procedure is both defensible to the stakeholders and fair in that it distinguishes well between good performers and underperformers. LESSONS FROM COMPETENCE ASSESSMENT: Large samples of behaviour are always necessary because of the domain specificity of competence and performance. The test content is considerably more important in determining which competency is being measured than the test format, and it is important to recognise that the process of problem-solving process is more idiosyncratic than its outcome. It is advisable to add some structure to the assessment but to refrain from over-structuring, as this tends to trivialise the measurement. IMPLICATIONS FOR PRACTICE PERFORMANCE ASSESSMENT: A practice performance assessment should use multiple instruments. The reproducibility of subjective parts should not be increased by over-structuring, but by sampling through sources of bias. As many sources of bias may exist, sampling through all of them may not prove feasible. Therefore, a more project-orientated approach is suggested using a range of instruments. At various timepoints during any assessment with a particular instrument, questions should be raised as to whether the sampling is sufficient with respect to the quantity and quality of the observations, and whether the totality of assessments across instruments is sufficient to see 'the whole picture'. This policy is embedded within a larger organisational and health care context.