Ambiguous decision points

Other elements of the decision point approach are the use of a battery of short term tests that either may eliminate the need for further testing of the chemical or may enable the verification of carcinogenic potential in one of four limited in vivo bioassays for carcinogenicity. The battery also adds essential information for data evaluation when an already completed chronic test series has yielded ambiguous results. 

The classical notion of risk in decision theory is primarily modeled using utility theory. Utility theory assumes that people are rational and should choose the option that maximizes the expected utility, which is the product of probability and payoff. Utility theory also assumes that all risk probabilities and payoff are known to a point estimate but does not allow ambiguity, or a variant form of uncertainty. In reality, however, uncertainty does occur when risk probabilities or payoff is missing or unknown. The subjective expected utility (SEU) model of utility theory proposed by Savage [26] argues that people s subjective preferences and beliefs, rather than objective probabilities, are used in the evaluation of an uncertain prospect for decision making. The SEU model is based on a set of seven axioms designed for consistent and rational behavior. 

Vq values are of theoretical and practical importance. In the language of physics, Vq is identified as the bottom of the conduction band, while in chemical terms, it is called the electron affinity of the liquid. As discussed in Section 7.6, Vq reflects the subtle balance of repulsive and attractive forces acting on the electron. The more negative the value, the greater the influence of attraction, while positive Vq values point toward the decisive influence of repulsion. Vq data are compiled in Table 3. The measured data were obtained either by the photoelectric method (see Section 6.2), by electron emission from liquids, or by comparison of photoconductivity and photoemission data (see Section 6.5). Data measured by the photoelectric effect may suffer from the effect of a charged double layer at the metal liquid interface. In principle, the values obtained by the electron emission method or from the comparison of photoconductivity and photoemission thresholds should be free from this ambiguity. 

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