Common use of PRECISION Clause in Contracts

PRECISION. In 2006 a subset of samples were reanalyzed by DRI using a newly-commissioned XRF instrument which replaced the XRF instrument used for the first two years of St. Louis – Midwest Supersite samples. This analysis provides a stringent test for the analysis methods contribution to collocated precision since different instruments were used. The last four columns of Table 4-5 report the comparisons for samples with the first analysis concentration at least ten times the DRI-reported MDL. Twenty-three of the forty reported elements had no concentration values exceed this threshold. Relative precision was better than 10% for all elements with at least five concentration values above the threshold.