Industry-wide performance in a pilot performance evaluation sample program for hazardous materials laboratories. 1. Elemental precision and accuracy
Thiss paper discusses the results of an interlaboratory study of the accuracy and precision of environmental laboratory results from 160 accredited laboratories operating in the state of California. The results from these laboratories were compared with a group of reference laboratories using student's t-test and Snedecor's F-test. The mean results for both groups were statistically identical, but the variance for the accredited laboratories was signifiicantly higher. The higher variance was due to several sources