Screening methods environmental variability

These different considerations have led us to assume that this method would be useful to investigate the behavioral effects of toxicants in preference to more natural approaches such as studies in field or semi-field conditions because it allows better control of treatment and conditioning parameters. Indeed, precise quantification of behavior is essential for determining whether a specific non-environmental variable affects the normal behavior. The sublethal effects of chemical pesticides have already been studied using restrained workers in the CPE assay [32-35]. It remains to establish whether the use of the CPE response as a measure of the sub-lethal effects of chemicals on honey bees can be a reliable indicator of the hazards associated with the exposure to sublethal doses of toxic compounds, and consequently can be included in standard screening proce-... 

The screening measures for total petroleum hydrocarbons screening are done differently in various states, regions, and individual laboratories. In fact, the data that are reported as total petroleum hydrocarbons are so variable that much caution should be exercised when attempting to compare or interpret the data. As analytical methods evolve in response to environmental needs, the definition of total petroleum hydrocarbons may become more closely related to reality rather than to the respective analytical method. 

An experiment involving a complex computer model or code may have tens or even hundreds of input variables and, hence, the identification of the more important variables (screening) is often crucial. Methods are described for decomposing a complex input-output relationship into effects. Effects are more easily understood because each is due to only one or a small number of input variables. They can be assessed for importance either visually or via a functional analysis of variance. Effects are estimated from flexible approximations to the input-output relationships of the computer model. This allows complex nonlinear and interaction relationships to be identified. The methodology is demonstrated on a computer model of the relationship between environmental policy and the world economy. 

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