Blind Proficiency Test (PT) Studies have been successfully completed by Coastal Bioanalysts, Inc. since 1991 (the first year EPA included toxicity data in their program), with over 400 toxicity test data points submitted to date.  Results of the two most recent studies are available at the bottom of this page.

 

The coefficient of variation (CV) for LC50s (acute tests) or IC25s (chronic tests), obtained from repeated testing of reference toxicants, provides a measure of test repeatability or precision.  The lower the CV value, the less variable the test results and the lower the frequency of false positive and false negative results. For WET testing, the EPA has compiled frequency distribution tables of intra-laboratory CVs for reference toxicant tests from a national data set.    Our CV values are consistently well below the national average and most are within the 10th or 25th percentile.

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Most important, the variability of a laboratory could affect compliance of a sample or product with a permit or regulatory limit.  It is critical to choose a laboratory that consistently produces sound and precise data.