Surveys are frequently used by businesses and governments to elicit information about the public’s preferences. They have become the most common way to gather preference information regarding goods, that are not (or are not yet) bought or sold in markets. In this paper we apply the standard neoclassical economic framework to generate predictions about how rational agents would answer such survey questions, which in turn implies how such survey data should be interpreted. In some situations, the standard economic model would be expected to have no predictive power. For situations where it does have predictive power, we compare different survey formats with respect to: (a) the information that the question itself reveals to the respondent, (b) the strategic incentives the respondent faces in answering the question, and (c) the information revealed by the respondent’s answer. Copyright Springer Science+Business Media, Inc. 2007Contingent valuation, Stated preference surveys, Incentive compatibility,

Signal transducers and activators of transcription (Stats) are activated by tyrosine phosphorylation in response to cytokines, and are thought to mediate many of their functional responses. Stat6 is activated in response to interleukin (IL)-4 and may contribute to various functions including mitogenesis, T-helper cell differentiation and immunoglobulin isotype switching. To evaluate the role of Stat6, we generated Stat6-null mice (Stat6 -/-) by gene disruption in embryonic stem cells. The mice were viable, indicating the lack of a non-redundant function in normal development. Although naive lymphoid cell development was normal, Stat6 -/- mice were deficient in IL-4-mediated functions including Th2 helper T-cell differentiation, expression of cell surface markers, and immunoglobulin class switching to IgE. In contrast, IL-4-mediated proliferation was only partly affected.

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Signal transducers and activators of transcription (STATs) are activated by tyrosine phosphorylation in response to cytokines and mediate many of their functional responses. Stat4 was initially cloned as a result of its homology with Stat1 (refs 4, 5) and is widely expressed, although it is only tyrosine-phosphorylated after stimulation of T cells with interleukin (IL)-12 (refs 6,7). IL-12 is required for the T-cell-independent induction of the cytokine interferon (IFN)-gamma, a key step in the initial suppression of bacterial and parasitic infections. IL-12 is also important for the development of a Th1 response, which is critical for effective host defence against intracellular pathogens. To determine the function of Stat4 and its role in IL-12 signalling, we have produced mice that lack Stat4 by gene targeting. The mice were viable and fertile, with no detectable defects in haematopoiesis. However, all IL-12 functions tested were disrupted, including the induction of IFN-gamma, mitogenesis, enhancement of natural killer cytolytic function and Th1 differentiation.

Contingent valuation (CV) is a survey-based method frequently used for placing monetary values on environmental goods and services not bought and sold in the marketplace. CV is usually the only feasible method for including passiveuse considerations in an economic analysis, a practice that has engendered considerable controversy. The issue of what a CV study tries to value is first addressed from the perspective of a policy-maker, and then the controversy over the inclusion of passive-use is taken up in more detail. The major issues and positions taken in the technical debate over the use of CV are summarized from a user's perspective. Key design and implementation issues involved in undertaking a CV survey are examined, and the reader is provided with a set of factors to examine in assessing the quality of a CV study.

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A literature search provides 83 studies from which 616 comparisons of contingent valuation (CV) to revealed preference (RP) estimates are made. Summary statistics of the CV/RP ratios are provided for the complete dataset, a 5% trimmed dataset, and a weighted dataset that gives equal weight to each study rather than each CV /RP comparison. For the complete dataset, the sample mean CV/RP ratio is 0.89 with a 95% confidence interval [0.81-0.96] and a median of 0.75. For the trimmed and weighted dat:asets, these sumrnarJ statistics are (0.77; [0.74~0.81]; 0.75) and (0.92; [0.81-1.03]; 0.94), respectively. Tne Spearman rank correlation coefficients between the CV and RP estimates for the three datasets are 0.78, 0.88, and 0.92, respectively, with the Pearson correlations a bit larger. Non-parametric density estimates are provided, as well as the results of regressions of the observed CV /RP ratios on the basic RP technique used and the broad class of goods valued.

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