A new perspective on the Dunnett procedure: filling the gap between NOEC/LOEC and ECx concepts.

The no-observed-effect concentration (NOEC) is known to be based on a wrong usage of hypothesis tests, and the use of confidence intervals is preferred. The purpose of the present study is to provide an easy and proper way to interpret ecotoxicological tests based on simultaneous confidence intervals associated with the commonly used Dunnett procedure, and to show how these intervals may allow one to infer ECx values (effective concentrations).