Weakly implementable social choice rules

Previous investigations have shown that a social choice function which is partially implementable must be characterized by pervasive veto power. This paper investigates how much additional latitude in the design of social choice functions, and how much relief from this vetoers result, can be achieved by examining multi-valued social choice rules and relaxing the requirement of partial implementability to a requirement that we call weak partial implementability. We find that the power structures which characterize partially implementable social choice functions, including the veto properties, also characterize weakly partially implementable social choice rules. The conclusion is that invoking multi-valuedness and implementation of appealing social choice rules in strong Nash equilibria. Our results apparently exhaust the possibilities for implementation in strong Nash equilibrium. If any implementation possibility results are to be achieved, they can apparently come only by weakening the equilibrium requirement.     

Estimating Probabilities Relevant to Calculating Relative Risk-Corrected Returns of Alternative Portfolios

In making all-or-none choices between alternative securities, Samuelson (1997b) suggested that investors of different risk-aversion should calculate from past samples of those securities their relevant Harmonic Means, or Geometric means, or other associative means representative of their respective degrees of relative-risk-aversion. Here it is shown how this learning procedure can be improved upon when you have prior knowledge that the securities have log-Normal distributions. Classical estimation theory, concerning consistent, efficient, and sufficient statistics, is shown to have a cash value by means of the calculable measure of (ex ante) “risk-corrected certainty equivalents.” Needed qualifications and testings are also presented.     

Status quo bias in decision making

Most real decisions, unlike those of economics texts, have a status quo alternative—that is, doing nothing or maintaining one's current or previous decision. A series of decision-making experiments shows that individuals disproportionately stick with the status quo. Data on the selections of health plans and retirement programs by faculty members reveal that the status quo bias is substantial in important real decisions. Economics, psychology, and decision theory provide possible explanations for this bias. Applications are discussed ranging from marketing techniques, to industrial organization, to the advance of science.     

Fast Mapping but Poor Retention by 24‐Month‐Old Infants

Four experiments explored the processes that bridge between referent selection and word learning. Twenty‐four‐month‐old infants were presented with several novel names during a referent selection task that included both familiar and novel objects and tested for retention after a 5‐min delay. The 5‐min delay ensured that word learning was based on retrieval from long‐term memory. Moreover, the relative familiarity of objects used during the retention test was explicitly controlled. Across experiments, infants were excellent at referent selection, but very poor at retention. Although the highly controlled retention test was clearly challenging, infants were able to demonstrate retention of the first 4 novel names presented in the session when referent selection was augmented with ostensive naming. These results suggest that fast mapping is robust for reference selection but might be more transient than previously reported for lexical retention. The relations between reference selection and retention are discussed in terms of competitive processes on 2 timescales: competition among objects on individual referent selection trials and competition among multiple novel name–object mappings made across an experimental session.     

An economist's non-linear model of self-generated fertility waves

Summary Standard one-sex linear models of Lotka or Bernardelli always approach asymptotically an exponential growth mode with stable age distribution. Realistic non-linear models need not possess this property. The present analysis uncovers a possibly realistic ease where an existent mode of balanced growth is 'unstable', giving way when slightly perturbed to an asymptotic every-other generation limit cycle of determinable amplitude, and which is stable. The nonlinear model utilizes the hypothesis of R. A. Easterlin that age-specific fertility will tend to be lower for age classes that are relatively swollen in total number. By virtue of the law of diminishing returns, wages and feeling of security will tend to be low for such swollen groups. A possible rebound in fertility in the 1980s is implicit in the Easterlin hypothesis.     

Book reviews

Law, socialism and social emancipation

Books Reviewed: M. Los, Communist Ideology, Law and Crime. St. Martin's Press: New York. 1988.

Paul Q. HirstLaw, Socialism and Democracy. London: Allen and Unwin 1986.

Citoyens et citoyennes

Review of: C. Pateman (1988), The Sexual Contract, Stanford University Press.

H.M. Hernes (1987), Welfare State and Women Power, Norwegian University Press.

Franco Crespi (1989), Azione sociale e potere, Il Mulino     

Effects of Track and Threat Information on Judgments of Hurricane Strike Probability

Although evacuation is one of the best strategies for protecting citizens from hurricane threat, the ways that local elected officials use hurricane data in deciding whether to issue hurricane evacuation orders is not well understood. To begin to address this problem, we examined the effects of hurricane track and intensity information in a laboratory setting where participants judged the probability that hypothetical hurricanes with a constant bearing (i.e., straight line forecast track) would make landfall in each of eight 45 degree sectors around the Gulf of Mexico. The results from 162 participants in a student sample showed that the judged strike probability distributions over the eight sectors within each scenario were, unsurprisingly, unimodal and centered on the sector toward which the forecast track pointed. More significantly, although strike probability judgments for the sector in the direction of the forecast track were generally higher than the corresponding judgments for the other sectors, the latter were not zero. Most significantly, there were no appreciable differences in the patterns of strike probability judgments for hurricane tracks represented by a forecast track only, an uncertainty cone only, or forecast track with an uncertainty cone—a result consistent with a recent survey of coastal residents threatened by Hurricane Charley. The study results suggest that people are able to correctly process basic information about hurricane tracks but they do make some errors. More research is needed to understand the sources of these errors and to identify better methods of displaying uncertainty about hurricane parameters.