Diagnostic data evaluation. Part IV. Evaluation of a check sample series to determine analyst performance

Data from a check sample series were subjected to diagnostic data evaluation. The chemical analyses that were performed were moisture, protein, and fat in meat products. Four performance outliers were identified (1 protein, 1 moisture, and 2 fat values). With the performance outliers excluded from the statistical evaluation, the analyst standard deviation ranged from 0.088 to 0.218 for protein, 0.145 to 0.393 for moisture, and 0.271 to 0.378 for fat. No bias was present. All laboratories were able to meet the established standards. With the limited number of samples it was not possible to attribute any reasons for the outliers.