No observed effect concentration: The highest concentration of a material in a toxicity test that has no statistically significant effect on the exposed population of test organisms compared to the controls. When derived from a life cycle or partial life cycle test, it is numerically the same as the lower limit of the MATC. Also called no observed adverse effect level (NOAEL) or no observed effect level (NOEL).
No Observable Effect Concentration. The highest concentration of a chemical at which no statistically significant, adverse effect is measurable on a test organism compared with controls. See LOEC
(No-observed-effect-concentration): The highest concentration of an effluent or toxicant that causes no observable adverse effects on the test organisms (i.e., the highest concentration of toxicant at which the values for the observed responses are not statistically different from the control) (EPA, 2000). Nonparametric hypothesis tests: Hypothesis test methods that are not dependent on data being normally distributed and exhibiting homogeneity of variance. These are also called distribution-free methods. Examples: Steel¡s Many-one and Kruskal-Wallis tests.
No observed effect concentration. The highest concentration of a substance in water that produces no toxic response in an animal.
The highest concentration of an effluent or a toxicant in a chronic bioassay that did not cause adverse effect statistically different from the control.