IS TEST VARIABILITY UNUSUALLY HIGH IN WET TESTS?
Comparisons of WET method precision with method precision for other analytes commonly limited in WPDES permits clearly demonstrate that the variability of the WET methods is within the range of variability experienced in other types of analyses. Several independent researchers and studies also have concluded that method performance improves when prescribed methods are followed closely by experienced analysts. Factors which can affect WET test variability, precision, and success include: the experience and skill of the laboratory analyst; test organism age, condition, and sensitivity; dilution water quality; temperature control; and the quality and quantity of food provided. The issue of WET variability has been discussed by a variety of groups in many different forums. Chapter 2.9 of The WET Guidance Document discusses WET variability and ways to control it in more detail. Other guidance has also been written by other groups such as the Society of Toxicology and Chemistry (SETAC) “Expe
