Wie ehrlich berichten männliche Jugendliche über ihr delinquentes Verhalten?

Survey-based studies on the prevalence and causes of deviant behaviour very much depend on the honesty of respondents. However, the validity of self-reports is rarely investigated. We report on a external validation of self-reported delinquency of male juveniles based on two survey samples — face-to-face interviews in households (N=309), and paper and pencil interviews in school (N=337) — which have been done in 1999 and 2000 in Freiburg and are used for record checks of self-reported police contacts both on the individual and aggregate level. Individual-level record checks reveal that a majority of respondents has honestly reported contacts with the police, while there are a considerable number of both ‘false negative’ and ‘false positive’ answers which come predominately from respondents with low educational and social status and of migration background. As these groups show high non-response rates as well, the correlation between delinquency and socio-economic status is likely to be underestimated. The school survey, on the other hand, yields higher and more realistic prevalence rates. However, comparisons between the two survey modes hint at differential effects of social desirability which question the validity of self-reports by respondents with high educational status. Survey results on self-reported delinquency should generally be interpreted with great caution, and more research on the mode effects of class room interviews are deemed necessary.     

A note on the correlation betweenS 2 and the least squares estimator in the linear regression model

In the following we consider the correlation betweenS ² and the least squares estimator in the linear regression model. We are interested in situations where these two statistics are uncorrelated though the errors are correlated. Conditions are developed without normality assumption, only assuming finite fourth moments of the error distributions. Support by Deutsche Forschungsgemeinschaft Grant No. Tr 253/1-2 is gratefully acknowledged.     

Benchmark Calculations in Risk Assessment Using Continuous Dose-Response Information: The Influence of Variance and the Determination of a Cut-Off Value

A benchmark dose (BMD) is the dose of a chemical that corresponds to a predetermined increase in the response (the benchmark response, BMR) of a health effect. In this article, a method (the hybrid approach) for benchmark calculations from continuous dose-response information is investigated. In the formulation of the methodology, a cut-off value for an adverse health effect has to be determined. It is shown that the influence of variance on the hybrid model depends on the choice of determination of the cut-off point. If the cut-off value is determined as corresponding to a specified tail proportion of the control distribution, P(0), the BMD becomes biased upward when the variance is biased upward. On the contrary, if the cut-off value is directly determined to some level of the continuous response variable, the BMD becomes biased upward when the variance is biased downward. A simulation study was also performed in which the accuracy and precision of the BMD was compared for the two ways of determining the cut-off value. In general, considering BMRs of 1, 5, and 10% (additional risk) the precision of the BMD became higher when the cut-off value was estimated by specifying P(0), relative to the case with a direct determination. Use of the square-root of the maximum-likelihood estimator of the variance in BMD estimation may provide a bias that is reflected by the cut-off formulation (downward bias if specifying P(0), and upward bias if specifying the cut-off, c, directly). This feature may be reduced if an unbiased estimator of the standard deviation is used in the calculations.     

A liberal paradox for judgment aggregation

In the emerging literature on judgment aggregation over logically connected propositions, expert rights or liberal rights have not been investigated yet. A group making collective judgments may assign individual members or subgroups with expert knowledge on, or particularly affected by, certain propositions the right to determine the collective judgment on those propositions. We identify a problem that generalizes Sen’s ‘liberal paradox’. Under plausible conditions, the assignment of rights to two or more individuals or subgroups is inconsistent with the unanimity principle, whereby unanimously accepted propositions are collectively accepted. The inconsistency can be avoided if individual judgments or rights satisfy special conditions. Earlier versions of this paper were presented at the LGS-4 Conference in Caen, June 2005, and at the World Congress of the Econometric Society in London, August 2005. We are grateful for the comments we received at both occasions as well as from anonymous referees. Franz Dietrich acknowledges financial support from the European Commission-DG Research Sixth Framework Programme (CIT-2-CT-2004-506084 / Polarization and Conflict Project). Christian List acknowledges the hospitality of the Social and Political Theory Program, RSSS, Australian National University.     

Bayesian group belief

If a group is modelled as a single Bayesian agent, what should its beliefs be? I propose an axiomatic model that connects group beliefs to beliefs of the group members. The group members may have different information, different prior beliefs and even different domains (algebras) within which they hold beliefs, accounting for differences in awareness and conceptualisation. As is shown, group beliefs can incorporate all information spread across individuals without individuals having to explicitly communicate their information (that may be too complex or personal to describe, or not describable in principle in the language). The group beliefs derived here take a simple multiplicative form if people’s information is independent (and a more complex form if information overlaps arbitrarily). This form contrasts with familiar linear or geometric opinion pooling and the (Pareto) requirement of respecting unanimous beliefs.     

Propositionwise judgment aggregation: the general case

In the theory of judgment aggregation, it is known for which agendas of propositions it is possible to aggregate individual judgments into collective ones in accordance with the Arrow-inspired requirements of universal domain, collective rationality, unanimity preservation, non-dictatorship and propositionwise independence. But it is only partially known (e.g., only in the monotonic case) for which agendas it is possible to respect additional requirements, notably non-oligarchy, anonymity, no individual veto power, or extended unanimity preservation. We fully characterize the agendas for which there are such possibilities, thereby answering the most salient open questions about propositionwise judgment aggregation. Our results build on earlier results by Nehring and Puppe (Strategy-proof social choice on single-peaked domains: possibility, impossibility and the space between, 2002), Nehring (Oligarchies in judgment aggregation: a characterization, 2006), Dietrich and List (Soc Choice Welf 29(1):19–33, 2007a) and Dokow and Holzman (J Econ Theory 145(2):495–511, 2010a).