Statistical scoring procedures applicable to laboratory performance evaluation

Two statistical scoring procedures based on p-values have been developed to evaluate the overall performance of analytical laboratories performing environmental measurements. The overall scores of bias and standing are used to determine how consistently a laboratory is able to measure the true (unknown) value correctly over time. The overall scores of precision and standing are used to determine how well a laboratory is able to reproduce its measurements in the long run. Criteria are established for qualitatively labeling measurements as Acceptable, Warning, and Not Acceptable and for identifying areas where laboratories should re-evaluate their measurement procedures. These statistical scoring procedures are applied to two real environmental data sets.