Rebuttal to Lowell et al. (2012) regarding Canada's environmental effects monitoring (EEM) program

Abstract

Huebert et al. (2011) suggested that the current methodused by the EEM program for calculating the BCI ispredisposed toward finding significant differences betweenreference and exposure areas because replicated exposure andreference stations are compared to the reference median.They further suggested an alternative method for calculatingthe BCI, using all pairwise comparisons between replicatedreference stations, and all pairwise comparisons between thereference and exposure stations. Whereas Huebert et al.(2011) were correct that using this alternative methodologyresults in smaller measured differences between referenceand exposure areas, they neglected to point out that it alsoartificially increases sample size (well beyond the number ofstations actually sampled). The result is that the alternativecalculation method has an equal probability of findingsignificant differences as does the method currently recom-mended by the EEM program. Thus, Environment Canadadoes not recommend incorporation of the alternativemethodology, because it provides no net gain and usesthe questionable practice of artificially increasing sample size.In conclusion, Environment Canada welcomes all newinformation with respect to good scientific practice that leadsto continued improvements to the EEM Program. In thisinstance, Environment Canada considered and addressed mostof the points made in the Huebert et al. (2011) article duringthe initial design of the program. Furthermore, carefulconsideration of the Huebert et al. (2011) calculation methodfor the BCI indicates that its disadvantages outweigh itsadvantages. The EEM program continues to evolve based onevaluation of new EEM data and methods of analysis as theybecome available.For further information regarding the regulations (includ-ing EEM requirements) please refer to the following websites: http://laws-lois.justice.gc.ca/eng/regulations and http://www.ec.gc.ca/esee-eem.Acknowledgment—The authors thank the EnvironmentCanada EEM ScienceCommittee members for their contribu-tion to this article.