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.     

Health care as a social security benefit: Institutional approaches to extending coverage

Reaching universal health‐care coverage requires an appropriate mix of compulsory contributory social insurance schemes, with mechanisms to include the informal‐economy population, and tax‐based social assistance for those whose incomes preclude their own contributions. This article urges a reversal of the trend that favours the separate development of social health insurance by separate health authorities and makes the case for the extension of health‐care coverage using existing formal‐sector social security schemes, not least because they have the necessary political backing and institutional structures. The article reviews reasons for the slow pace of coverage extension to date, and stresses the added value of incorporating health care as a social security benefit while also acknowledging the importance of retaining linkages between statutory and well‐regulated community‐based or micro health‐insurance schemes.