Baby talk to the babyfaced

The power of an infantile appearance to elicit baby talk was investigated by assessing the use of baby talk in task instructions to four-year-old children, who were portrayed as either relatively babyfaced or maturefaced. Men and women taught two tasks to a randomly selected boy or girl via a telephone conversation after being shown a photograph, which presumably depicted the child whom they were instructing. Paralleling facial differences between babies and adults, babyfaced children had rounder faces, larger eyes, thinner eyebrows, and smaller noses than the maturefaced. As predicted, adults used more baby talk when instructing babyfaced than maturefaced children. This effect was manifested in linguistic indicators of baby talk (slow timing and high clarification, simplification, and attention maintenance), as well as in paralinguistic indicators of baby talk (high pitch and changing intonation). The receipt of linguistic baby talk, in turn, facilitated the child's ability to choose a card which matched the one being described. The fact that facial babyishness influenced baby talk even when baby- and maturefaced children were equated in age, attractiveness, and perceived competence suggests that a small approximation to the craniofacial qualities that distinguish infants from adults may in and of itself be sufficient to elicit this speech register.This research was supported by NIMH grant #BSR5 R01 MH42684 to the first author. The authors would like to express their appreciation to the Brandeis University and Wellesley College Daycare Centers for their cooperation in this research. Thanks are also extended to Stacy Silberman for serving as one of the experimenters and to Becky Gilbert, Katina Lawdis, Sheryl Levy, and Liz Tighe for their help in coding the data.     

The many meanings of sleep

Reductions in sleep are concomitant with night shift work. Data are presented showing that these robust differences in sleep are even present in experienced permanent night shift workers who most prefer to work nights. A model is presented which relates these reductions to chronic sleep deprivation. This, in turn, may be associated with performance decrements, and lead to accidents and illness. Better work schedule selection, worker training programs, and preventive medical action are unproven but promising approaches to overturning this model.     

Confidence to be given findings derived from fixed-period definitions of migration

Some of the errors in measurement of migration and its determinants that occur with the use of fixed-period data are identified. Consideration of this issue yields a typology of studies based on the nature of the determinants related to migration. Sources of distortion are numerated. The logical severity of each distortion is detailed. Use of the typology permits an appraisal of the potential confidence to be given to the validity of findings associated with classes of migration research which use fixed-period data. A test case is examined to illustrate the usefulness of the typology.This research was supported in part by the NSF Grant No. SOC76-81767, for the study, "A Test of Competing Explanations for Migration Differentials." Funds for computer time and technical assistance were also provided by the Department of Sociology, The University of Tennessee, Knoxville.     

Relative Risk Aversion: What Do We Know?

The relative risk aversion measure that represents the risk preferences of a decision maker depends on the outcome variable that is used as the argument of the utility function, and on the way that outcome variable is defined or measured. In addition, the relationship between any two such relative risk aversion measures is determined by the relationship between the corresponding outcome variables. These well-known facts are used to adjust several reported estimates of relative risk aversion so that those estimates can be directly compared with one another. After adjustment, the significant variation in the reported relative risk aversion measures for representative decision makers is substantially reduced. JEL Classification: D81     

A New Kind of Case Study: Using Business Bestsellers in the Business Policy Course

The undergraduate Business Policy (Strategic Management) course is often taught by using the case method of instruction. Cases are generally regarded as especially good vehicles for giving students an understanding of the general management view of an organization. The authors believe that it is useful for students to learn much about the strategy of at least one corporation in-depth. They use a business bestseller about a particular company or industry each semester for this purpose. All undergraduate students prepare the same written assignments on this company or industry using the business bestseller as a starting point. Experience in using the business bestseller as the basis of a written assignment in the business policy course has been very positive. Students both enjoy and profit from an assignment that focuses in-depth on a major firm or industry that they can comprehend and the evolution of which they can follow. Alumni often indicate that they continue to track the company or industry after graduation. The authors believe that such written assignments help prepare students of business strategy for the real world. This revised version was published online in July 2006 with corrections to the Cover Date.     

Decision-Making with Heterogeneous Sources of Information

In any model the values of estimates for various parameters are obtained from different sources each with its own level of uncertainty. When the probability distributions of the estimates are obtained as opposed to point values only, the measurement uncertainties in the parameter estimates may be addressed. However, the sources used for obtaining the data and the models used to select appropriate distributions are of differing degrees of uncertainty. A hierarchy of different sources of uncertainty based upon one's ability to validate data and models empirically is presented. When model parameters are aggregated with different levels of the hierarchy represented, this implies distortion or degradation in the utility and validity of the models used. Means to identify and deal with such heterogeneous data sources are explored, and a number of approaches to addressing this problem is presented. One approach, using Range/Confidence Estimates coupled with an Information Value Analysis Process, is presented as an example.     

Higher‐Order Improvements of a Computationally Attractive k‐Step Bootstrap for Extremum Estimators

This paper establishes the higher‐order equivalence of the k‐step bootstrap, introduced recently by Davidson and MacKinnon (1999), and the standard bootstrap. The k‐step bootstrap is a very attractive alternative computationally to the standard bootstrap for statistics based on nonlinear extremum estimators, such as generalized method of moment and maximum likelihood estimators. The paper also extends results of Hall and Horowitz (1996) to provide new results regarding the higher‐order improvements of the standard bootstrap and the k‐step bootstrap for extremum estimators (compared to procedures based on first‐order asymptotics). The results of the paper apply to Newton‐Raphson (NR), default NR, line‐search NR, and Gauss‐Newton k‐step bootstrap procedures. The results apply to the nonparametric iid bootstrap and nonoverlapping and overlapping block bootstraps. The results cover symmetric and equal‐tailed two‐sided t tests and confidence intervals, one‐sided t tests and confidence intervals, Wald tests and confidence regions, and J tests of over‐identifying restrictions.     

Use of Quality-Adjusted Life Year Weights with Dose-Response Models for Public Health Decisions: A Case Study of the Risks and Benefits of Fish Consumption

Risks associated with toxicants in food are often controlled by exposure reduction. When exposure recommendations are developed for foods with both harmful and beneficial qualities, however, they must balance the associated risks and benefits to maximize public health. Although quantitative methods are commonly used to evaluate health risks, such methods have not been generally applied to evaluating the health benefits associated with environmental exposures. A quantitative method for risk-benefit analysis is presented that allows for consideration of diverse health endpoints that differ in their impact (i.e., duration and severity) using dose-response modeling weighted by quality-adjusted life years saved. To demonstrate the usefulness of this method, the risks and benefits of fish consumption are evaluated using a single health risk and health benefit endpoint. Benefits are defined as the decrease in myocardial infarction mortality resulting from fish consumption, and risks are defined as the increase in neurodevelopmental delay (i.e., talking) resulting from prenatal methylmercury exposure. Fish consumption rates are based on information from Washington State. Using the proposed framework, the net health impact of eating fish is estimated in either a whole population or a population consisting of women of childbearing age and their children. It is demonstrated that across a range of fish methylmercury concentrations (0-1 ppm) and intake levels (0-25 g/day), individuals would have to weight the neurodevelopmental effects 6 times more (in the whole population) or 250 times less (among women of child-bearing age and their children) than the myocardial infarction benefits in order to be ambivalent about whether or not to consume fish. These methods can be generalized to evaluate the merits of other public health and risk management programs that involve trade-offs between risks and benefits.