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Use of power analysis to develop detectable significance criteria
for sea urchin toxicity tests
R.S. Carr, J.M. Biedenbach
USGS, Biological Resources Division, Marine
Ecotoxicology Research Station, TAMU-CC, Center for Coastal
Studies, NRC Suite 3200, 6300 Ocean Drive Corpus Christi,
TX 78412, USA
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Abstract
When sufficient data are available, the statistical power of
a test can be determined using power analysis procedures. The term
detectable significance" has been coined to refer to this criterion
based on power analysis and past performance of a test. This power
analysis procedure has been performed with sea urchin (Arbacia
punctulata) fertilization and embryological development data
from sediment porewater toxicity tests. Data from 3100 and 2295
tests for the fertilization and embryological development tests,
respectively, were used to calculate the criteria and regression
equations describing the power curves. Using Duunett's test, a minimum
significant difference (MSD) (ß = 0.05) of 15.5% and
19% for the fertilization test, and 16.4% and 20.6% for the embryological
development test, for a <0.05 and a 0.01, respectively,
were determined. The use of this second criterion reduces type I
(false positive) errors and helps to establish a critical level
of difference based on the past performance of the test. ©
1999 Published by Elsevier Science Ltd and AEHMS. All rights reserved.
Keywords: Arbacia punctulata; Porewater toxicity; Minimum
significant difference (MSD)
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