The evaluation of the outcome of a ring test has to assess the uncertainty of the results by determining the repeatability and the reproducibility of the data sets. This evaluation is the most important step in defining the validity of an individual test method or even a whole set of tests. The results of the aquatic and the terrestrial basic test set are statistically analyzed by two parameters: reproducibility standard deviation and repeatability standard deviation (ISO 5725-1, 1994).
The discussion of the statistical performance of the ring test is focused on the basic test battery and the waste material WOO and INC, fulfilling the given requirements such as number of data sets, calculable test results and valid test procedure according to the guidelines and SOPs (the test substrate SOI was excluded here due to its low toxicity; very often no EC50 could be determined).
The comparison of repeatability standard deviation s r and reproducibility standard deviation s R covers a range between 2.16 and 15.0. 42% of the biotest results are within a s R/s r ratio of 4 and about 85% are within a range for the s R/s r ratio from 2 and 8, taking into account that this range already covers influence factors like eluate preparation or the use of different test species. It can be summarized that the basic test set forms a reliable methodology for waste ecotoxicity tests, which can be optimized with experiences gained in the ring test (see also Chap. 1.5)